George Galloway breached the broadcasting rules on impartiality during his shows on Press TV, the news channel funded by the Iranian government, Ofcom said today.
The Respect MP accused the Israeli government of using "a Nazi tactic", conducting a "brutal apartheid-style occupation" and committing "war crimes" in various editions of his discussion programmes broadcast during the Gaza conflict in January.
Ofcom said the Real Deal and Comment shows, hosted by Mr Galloway, had not ensured that appropriate weight was given to a range of views.
While it was not against the broadcasting code for Mr Galloway to express his opinions, Ofcom said, alternative viewpoints had to be aired on controversial issues.
Ofcom received complaints about two editions of Mr Galloway's weekly phone-in programme Comment and one of his current affairs show The Real Deal.
In its ruling today, Ofcom said: "Taking the programmes as a whole, Ofcom noted that there were some but extremely limited contributions that could be labelled as being broadly supportive of the actions of the Israeli state in Gaza during January 2009.
"It should be noted that where a matter of major political controversy is being discussed - as here - the broadcaster must ensure that 'an appropriately wide range of significant views must be included and given due weight in each programme or in clearly linked and timely programmes'.
"This is especially important where a presenter is known to have strongly held views on the subject being discussed in the programme and clearly makes his position clear throughout the programme."
Ofcom said the "overwhelming majority" of the programmes' content was pro-Palestinian and highly critical of Israeli policy, and Mr Galloway spoke "from an entirely pro-Palestinian point of view".
Not one telephone call and only limited texts and emails were taken from people with pro-Israel views, the watchdog said.
In the January 8 edition of Comment, Mr Galloway said of Israeli policy: "Collectively punishing people is a Nazi tactic"; he said the Palestinians were under the "iron heel of a brutal apartheid-style occupation" and asked "Which other country could murder United Nations employees?"
On the show a week later, Mr Galloway described the Israeli military incursion into the Gaza Strip as "...a war crime. It is a scandal of the greatest proportions".
Press TV argued that it had complied with the broadcasting code by giving viewers with alternative viewpoints the chance to respond to Mr Galloway's comments by telephone, email and text message.
On Mr Galloway's assertion that Israel was guilty of war crimes, Press TV told Ofcom that it "allowed people to contribute to the show who believe that Israel has not committed a war crime.
"However, the number of people who believe the latter is only a small percentage, and therefore the contributions to the show reflect that."
Ofcom rejected the broadcaster's contention that the presence of the journalist Jeff Steinberg on The Real Deal had provided an Israeli perspective on the debate, saying he appeared as a commentator rather than someone putting the Israeli position.