International Development Secretary Hilary Benn yesterday appealed to all sides in the Lebanon to observe the ceasefire so essential supplies could get to the thousands forced to flee fighting.
Mr Benn, who flew in to Beirut to see conditions on the ground, announced a further £6 million of British aid, taking the total UK contribution to £12.5 million.
The visit came as his father, veteran Labour politician Tony Benn, branded the British Government a disgrace over its conduct in the Middle East.
Following a tour of the city's bomb-damaged southern suburbs, Hilary Benn said the country was facing a "humanitarian emergency".
"Nearly one million people have had to flee their homes and some are in urgent need of basic supplies, although people are starting to return. Infrastructure has been badly damaged and aid has struggled to get through," he said. "It is crucial all sides abide by their obligations under international humanitarian law and, as a priority, allow safe access for humanitarian organisations to provide help to those who urgently need it.
"The best way to do this is to make sure the ceasefire holds."
Mr Benn, who held talks with Lebanese Prime Minister Fouad Sinioria, said he was particularly concerned about the plight of the estimated 100,000 people who had been stranded by the fighting south of the Litani River.
The UK funding announced yesterday will be targeted at the area, including mine clearance and bridging to replace those destroyed in Israeli airstrikes.
"This will assist thousands displaced from their homes, and provide help to get aid to those who've been cut off by fighting," Mr Benn said.
Mr Benn, who was reportedly critical of Tony Blair's refusal to call for an immediate ceasefire, hit out at the scale of the damage caused by the Israelis to the civilian infrastructure.
"Israel had every right to defend itself against Hezbollah and the attacks - the rockets that were coming in. Nobody questions that," he said.
"On the other hand I have to say that attacking power stations and water treatment plants - I'd find it very difficult to describe that as proportionate.
"There is no doubt that the humanitarian emergency here is very considerable."
Mr Benn also insisted the United Nations Security Council resolution which led to the ceasefire made clear that Hezbollah must disarm.
"There can only be one authority in Lebanon, that's got to be the government. There can only be one armed body and that's got to be the armed forces of Lebanon," he said.