Hezbollah's leader threatened tonight that he will turn south Lebanon into a "graveyard for Israeli soldiers".

In a televised speech, Sheikh Hassan Nasrallah backed the Lebanese proposal to deploy troops to the south but said that Washington was trying to impose Israeli demands on Lebanon through an "unfair" and "unjust" draft resolution. The Hezbollah leader said that the seven-point plan presented by the Lebanese government was the least the country should accept as part of a draft resolution to end the fighting.

Sheikh Nasrallah said that his guerrilla fighters’ ability to fire rockets on Israel remained as strong as ever and he warned Arab residents of Haifa to leave Israel’s third city which has been subjected to repeated deadly rocket fire by Hezbollah.

Earlier today Israeli ministers approved a broadening of the ground war in southern Lebanon after the commander of the Israeli offensive was sacked and pressure mounted on the military to score a decisive victory over Hezbollah.

In Britain, a Labour MP announced that he was leaving his Government defence post over the conflict in Lebanon as more than 130 MPs - around half of them Labour - issued a demand for a recall of Parliament to discuss the Lebanon crisis.

Jim Sheridan, Labour MP for Paisley and Renfrewshire North, said he was standing down from his post as parliamentary private secretary to the defence ministers.

"The reason I am resigning is the current conflict in the Middle East and once again the Palestinian situation has been put on the back burner," he told Sky News.

Mr Sheridan added: "I don’t expect my resignation will have any significant impact on the Prime Minister’s objectives in the Middle East, which I genuinely believe to be honourable on his part, but I don’t believe they reflect the core values of the Labour Party or indeed the country".

After a six-hour meeting this morning, the Israeli Security Cabinet authorised the army to push into Lebanon as far as the Litani River, 30km (18 miles) across the border. Of the 12 senior ministers present, nine agreed to the plan and three abstained.

As diplomats in New York and Beirut continued their attempts to secure a UN resolution that will halt the bloodshed, Israel's Deputy Prime Minister, Eli Yishai, said a widened offensive could take more than a month.

"The assessment is it will last 30 days. I think it is wrong to make this assessment. I think it will take a lot longer," he said.

The security cabinet decision authorises Amir Peretz, the Defence Minister, and Ohud Elmert, the Prime Minister, to step up the offensive but does not obligate them to act.

Times Recommends

• Michael Jackson: Not the final chapter
• Indian Army spends10m rupees on golf buggies
• Brüno toned down for 15 rating