The BBC Trust said today it would not overrule the decision not to broadcast a humanitarian appeal for Gaza.
The corporation's director general, Mark Thompson, refused to air the appeal from the Disasters Emergency Committee (DEC) last month on the grounds that it would have risked compromising the BBC's impartiality.
The Trust asked Mr Thompson to review the BBC arrangement with the DEC, which dates from 1971, to see if it was still appropriate in the modern broadcasting environment.
The BBC's refusal to air the DEC appeal caused a storm of protest - around 40,000 complaints were lodged with the corporation, and a further 200 appeals were made to the Trust.
Sir Michael Lyons, the Trust's chairman, said in dealing with these appeals, the board had considered whether the director general's decision had been made in accordance with the relevant BBC guidelines.
"We recognise that the director general's decision was a matter of great controversy for many members of the public," he said.
"However, having carefully examined the director general's reasons, the Trust believes he acted correctly throughout, and we are satisfied that the decision the director general took was reasonable given the importance of preserving the reputation of the BBC for impartiality."
Sky News also refused to show the appeal, but ITV, Channel 4 and Five did televise the three-minute broadcast.
More than 100 MPs from all parties signed an early day motion in the House of Commons criticising the decison of the BBC and Sky News.
Mr Thompson set out his reasons for refusing to show the appeal in his blog on January 29.
He wrote: "Gaza remains a major ongoing news story, in which humanitarian issues - the suffering and distress of civilians and combatants on both sides of the conflict, the debate about who is responsible for causing it and what should be done about it - are both at the heart of the story and contentious.
"We concluded that we could not broadcast a free-standing appeal, no matter how carefully constructed, without running the risk of reducing public confidence in the BBC's impartiality in its wider coverage of the story."
The danger for the BBC was that broadcasting an appeal could be interpreted as taking a political stance on an ongoing story, he added.
Sir Michael said the Trust considered this to be a reasonable argument.
"It is not in the Trust's remit to second-guess (Mr Thompson's) editorial decisions, nor should it be," he said.
"Our role is to ensure he reaches those decisions with care, and free from undue influence from any quarter."
The suggestion had been made that a disclaimer could have been shown before the appeal to distance the BBC from it politically, but the Trust said in its written judgment that such a disclaimer would not have been effective.
The Trust also said that while the opinions of viewers and listeners were relevant, the director general had to exercise his own judgment on matters of BBC impartiality.
"We will not reopen the question of this particular DEC appeal," Sir Michael added.
"However, we are mindful of the degree of public concern it aroused.
"We have therefore asked the director-general to explore any wider lessons that may be drawn from this episode through discussions with DEC and with other broadcasters.
"In particular we have asked him to take a view on whether the BBC agreement with DEC, which dates from 1971, and the associated criteria for considering appeals, are still appropriate for today's changed conditions."
The Gaza broadcast was not the first to be turned down by the BBC on impartiality grounds.
The corporation refused to show an appeal for Lebanon and northern Israel during the 2006 conflict there because aid would be directed mainly to one area only - Lebanon.
DEC said it felt the criteria for launching an appeal had been met in the case of Gaza.
"We respect the BBC's right to decide on whether to broadcast the appeal but we believe it would be unfortunate if the additional hurdle imposed in this specific situation set a precedent for future appeals," the DEC said in a written statement.
"The three criteria agreed with broadcasters for launching DEC appeals - scale of need, ability of DEC members to deliver aid, and evidence of public support - have stood the test of time, as has our membership's commitment to delivering, impartially, help to those in need.
"Over the last 45 years, the DEC, with the help and support of the BBC and other broadcasters, has made a significant contribution to the alleviation of suffering - a contribution that all the organisations involved can be proud of."
The DEC said the appeal had raised £5 million, but more was needed to help ease the plight of people affected by the conflict in the densely-populated coastal enclave, which killed more than 1,300 Palestinians.
Israel launched military action against Hamas, the Islamic group that controls Gaza, on December 27 and only halted the attacks 22 days later.
The main appeal considered by the Trust was lodged by legal firm Hickman and Rose on behalf of two Gaza residents and a UK citizen.
Anna Mazzola, a solicitor with the company, said it would consider the Trust's ruling.
"But it is highly likely that we will go ahead with a judicial review of the decision," she said.
"The time frame for this depends on a number of factors, but we would hope to proceed with it fairly quickly."
The Liberal Democrats said the BBC should reconsider its decision.
Their culture, media and sport spokesman Don Foster said: "The BBC Trust has to allow the BBC director general to make these types of editorial decisions.
"However, that doesn't change the fact that Mark Thompson got this decision wrong.
"No one seriously believes that any of the channels that did screen the appeal have undermined their impartiality. The BBC must now reconsider its position for future appeals."
Richard Burden, Labour MP for Birmingham Northfield, who tabled the early day motion on the issue, said the Trust's ruling showed a "strange set of priorities".
"Many people - including me - have strong opinions on the Israel-Palestine conflict," he said.
"The DEC appeal is not about taking sides in this conflict. It never was about that.
"It is about getting essential humanitarian aid to the people of Gaza - now, when they need it most.
"The thousands of people who have contacted the BBC show that viewers and listeners understand this distinction even if the BBC Management and Trust seem to have such difficulty in doing so.
"Nearly 200 MPs in the UK have signed a motion expressing astonishment at the BBC's refusal to broadcast the appeal. None of us question the right of the BBC to make the editorial decisions they choose. But many of us seriously question their judgment here."
Screening the Gaza broadcast was no more of a threat to the corporation's impartiality than showing similar appeals fro Congo and Darfur, he said.
"I note that the BBC Trust are saying they will now review the way in which they handle DEC appeals in the future.
"I just hope that does not mean they will refuse to broadcast appeals for the Congos and Darfurs of the future in the way they are now refusing to broadcast the Gaza appeal.
"They should get their priorities straight and do their bit to help those charities involved in the DEC appeal to get the aid that is so desperately needed in to Gaza."