BBC News with Marion Marshall

The United Nations special envoy Kofi Annan has warned that the current peace plan for Syria may be the last chance to avoid civil war. He said such conflict couldn't be allowed to happen and its implications would be frightening. Mr Annan was speaking after he briefed the UN Security Council on the situation in Syria. Barbara Plett reports from New York.

The tone of Kofi Annan's comments was bleak . He acknowledged that the government's use of heavy weapons had declined somewhat since the ceasefire declaration, but he said the level of violence remained unacceptable. He tried to sound a note of optimism, saying the presence of the UN military observers had helped to bring calm in places, and the deployment of the full team by the end of the month would make quite a difference . But he suggested that the peace plan might fail, and warned that this could mean full-scale civil war. Western envoys, such as the US ambassador Susan Rice, signal that they do stand ready to seek tougher action at the council, like sanctions; but it's almost certain that Russia and China wouldn't support such moves.

Libyan security forces have prevented armed protesters from storming the headquarters of the prime minister in Tripoli. The attackers were former rebels from outside the capital, who fought to overthrow Colonel Gaddafi last year, and were demanding compensation promised by the government. One member of the security forces was killed. Nasir al-Mani, who's a spokesman for the prime minister, said the government needed greater protection.

"We regret today's incident. There may have been civilians among the protesters who came to protest peacefully, but may have been exploited by others. We stress that while we try to be accommodating, we may have to use force to protect the state and its prestige ."

American military trainers have returned to Yemen to help counter recent gains by al-Qaeda militants and their supporters. Washington said a number of US personnel were working with the Yemeni armed forces. It didn't disclose the precise nature of their work or how many of them were involved.

The leader of the far-left Syriza group in Greece, Alexis Tsipras, has urged the country's two traditional big parties to abandon their commitment to austerity, saying voters had rejected it in Sunday's election. Mr Tsipras has been three days to try to form a coalition government. Here's our Athens correspondent Mark Lowen.

"Mr Tsipras, will you succeed in forming a government?"

There was no answer from Greece's young leftist leader as he entered the presidency building, given a mandate to attempt to form a new coalition here. Alexis Tispras has now begun talks with a range of parties – mainly from the left – but on one condition that Greece's international bailout and the austerity measures that accompany it are torn up . The likelihood of now forming a government is fading fast with a probability of fresh elections. That would hold up the next installment of the country's loan, and again raise the spectre of Greece's bankruptcy.

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Russia's parliament has approved Dmitry Medvedev as the country's new prime minister. The appointment comes a day after Vladimir Putin returned to the presidency. The job swap between the two men has angered opponents who said it shows how power in Russia is held within a tight circle.

The jailed Ukrainian opposition leader Yulia Tymoshenko has indicated that she's ending her hunger strike. Her daughter said she'd agreed to be moved from prison to a hospital where she will be treated by a German doctor. Yulia Tymoshenko started refusing food more than two weeks ago after complaining that she'd been beaten in prison. Her treatment had sparked diplomatic protests. Earlier, Ukraine called off the European Summit it was due to host later this week after many countries declared a boycott.

The Sudanese government has informed the joint United Nations-African Union peacekeeping mission that it cannot continue with direct flights between its regional support base in Uganda and its operations in Darfur. A spokesman for the mission told the BBC that flights would now have to be rerouted via Khartoum, the capital of Sudan, which would be costly and difficult.

A paralyzed British woman has become the first person to complete a marathon in a bionic suit. Claire Lomas finished the London Marathon 16 days after starting the race with 36,000 other people. Mrs Lomas was paralyzed from the chest down in a horse-riding accident five years ago. Hundreds of people lined the streets as she made her final steps to complete the race. She said she hadn't been given an official medal because she didn't finish on the day of the race. But 14 other runners gave her their medals.

"Now it's never really first*marathon because it's also a reason I stayed. I spent it for Spinal Research. They did as much as they can on the awareness of spinal injury. And then, eventually there were 14 medals – such ** nice on the cage. It's amazing."

Mrs Lomas's bionic ReWalk suit allows her to walk by detecting shifts in her balance.

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