The United Nations was forced to halt all attempts to deliver humanitarian aid to the thousands of civilians stranded in southern Lebanon last night, despite repeated Israeli assurances of secure corridors. The move, echoed by major aid agencies, followed Israeli threats to destroy any vehicle operating south of the Litani river.
Jack Redden, from the UN refugee agency UNHCR, said: "In many places, particularly in the far south, it is completely impossible to get anything into that area."
The head of Médecins Sans Frontières' (MSF) mission in Lebanon, Chris topher Stokes, described Israeli assurances of protected aid corridors as delusional. "For many days, the concept of humanitarian corridors has been used to mask the reality," he said. "It is impossible to get safe access to the villages in the south."
MSF was forced physically to carry more than four tons of aid over the river on Monday and then reload the supplies on to trucks. Aid efforts were already severely compromised by the Israeli air force's bombing of the last remaining bridge over the Litani.
"We do not have real access to the people most in need," Mr Stokes said. "By the same token, people who want to flee the affected region or seek help have no guarantees that they can do so safely, contrary to what is suggested by this talk of a humanitarian corridor."
The Red Cross claimed that there were up to 100,000 Lebanese trapped in the cut-off areas.
The mounting humanitarian crisis came as Tony Blair flew to Barbados yesterday for his postponed holiday, leaving charities and Labour MPs angry and frustrated at the UK's "shameful" failure to do more to establish humanitarian corridors in Lebanon.
Margaret Beckett, the Foreign Secretary, promised Britain would be pushing for the humanitarian corridors to be established as a priority, but yesterday she was still on a caravanning holiday in France.
The Foreign Office said the Foreign Secretary was on stand-by to fly to New York for a UN meeting, but it was unclear when that would happen.
Before flying off to join his wife, Cherie, and children at the villa in Barbados owned by Sir Cliff Richard, Mr Blair did a round of interviews and promised that the UK would be more involved in providing humanitarian aid and rebuilding Lebanon's infrastructure.
But the lack of diplomatic momentum to allow humanitarian aid through has dismayed some of those on the front line who are trying to reach those trapped by the conflict.
Speaking in Beirut, where he is helping the aid effort, Dominic Nutt of Christian Aid said: "It does stick in the craw that people are going on holiday while the humanitarian crisis is still going on." He said it was a moral and legal duty under international law to provide unfettered access to humanitarian aid, but so far that was being denied.
Clare Short, the former cabinet minister in charge of international aid, said it was a "scandal" that more was not being done to deliver humanitarian aid.
Ms Short, who resigned as Secretary of State for International Development over the Iraq war, attacked what she called the UK's "shameful" failure to make sure that humanitarian aid reached the Lebanese, and the decisions by Mr Blair and Mrs Beckett to go on holiday with the crisis unresolved. "On top of all the killing and the destruction, we're now heading for a major humanitarian disaster - hunger, disease and the rest of it," she warned.
In his interview with the BBC, Mr Blair defended his decision not to call for an immediate ceasefire, saying the situation was complicated. Mr Blair insisted that he would stay in charge of the Government's response to the conflict while on his break and would keep in touch with other world leaders. Mr Blair said the long-term solution involved putting the government of Lebanon back in charge of its country and a return to the Israel-Palestine question, "which I think is completely fundamental to the whole of the issues in the Middle East".
Even getting aid into Lebanon itself has become increasingly problematic. The only land crossing open to UNHCR is on the northern border at al-Aarida, 100 miles north of the capital, Beirut. The price of fuel has rocketed to more than £200 a tank, Beirut's airport is almost completely unusable and any aid arriving by sea has to get a green light from Israel's naval blockade before it is allowed to proceed.