Syria and the United Nations have signed an agreement on the ground rules for observers monitoring a shaky ceasefire negotiated by UN-Arab League envoy Kofi Annan.

Syria's foreign ministry says the agreement will allow the Annan plan to succeed and will facilitate the UN observer mission, while at the same time respecting Syria's sovereignty.

A spokesman for Mr Annan says the agreement covers the functions of the mission and the Syrian government's responsibilities.

Meanwhile, UN secretary-general Ban Ki-moon has delivered his first progress report since the initial team of UN observers arrived in Syria last Sunday.

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Mr Ban told a briefing to the United Nations in New York the situation in Syria remains "highly precarious" despite the ceasefire plan, which began on April 12.

He says the Syrian government has not complied with the terms of the peace deal, but there remains "opportunity for progress".

He called for tougher sanctions against Damascus and for the small UN observer team already on the ground to be increased in size.

He says he wants 300 unarmed observers sent for three months and has asked the UN Security Council to "move quickly" to approve the deployment, given there is "deeply troubling evidence" that Syria is pursuing its deadly crackdown despite agreeing to halt the violence.

But Mr Ban admitted increasing the observer mission "is not a decision without risk".

"The past few days, in particular, have brought reports of renewed and escalating violence, including the shelling of civilian areas, grave abuses by government forces and attacks by armed groups," he said.

"Despite assurances from the government there has been no meaningful progress on the ground, this is unacceptable.

"I call on the Syrian authorities to recognise the full urgency of the situation and permit UN agencies and international relief organisations to organise a major humanitarian field operation to help people in need."

Mr Ban also demanded Syria ensure the monitors have full freedom of movement to cover the country.

So far the monitors have been to Damascus, but have not been allowed to go to the most obvious troubled spot, Homs, where intense shelling of rebel held areas has continued.

Mr Ban says the withdrawal of those heavy weapons, troops and tanks is critically important.

At least seven people have died in violence across Syria in the past 24 hours, according to human rights monitors.

Road to civil war

As Mr Ban delivered his speech, the French government warned Syria is on the road to civil war - or even regional war - if it does not comply with the peace plan.

French foreign minister Alain Juppe said at a meeting of the Friends of Syria Coalition in Paris: "the Annan plan is a guarantee of peace and freedom - its failure is the path to civil, even regional, war. Let us face our responsibility".

He said the "opposition has fulfilled its obligations under the Annan plan" and that "groups on the ground have respected the ceasefire" despite problems of coordination "made very hard by the provocations of the regime".

"We cannot say the same for the Syrian regime. It is pursuing without shame repressive tactics that have already left dozens more dead since the ceasefire was due to go into effect," he charged.

He called for tough sanctions against Damascus and for the small UN observer team already on the ground to be boosted to 300 or 400-strong and made "robust and credible" with land and air transport to cover the country.

French president Nicolas Sarkozy accused the Syrian regime of trying to wipe out Homs altogether.

He said the only solution was to impose humanitarian corridors so that relief can get through.

Mr Ban's assessment also prompted the United States to call for tougher sanctions against the Syrian government.

US secretary of state Hilary Clinton told Friends of Syria Coalition the Security Council must introduce tougher sanctions including travel, financial sanctions, and an arms embargo to force the Assad regime to comply with the UN peace plan.

The Paris meeting included foreign ministers and envoys from Germany, Saudi Arabia, Canada, Egypt, the UAE, Spain, the United States, Italy, Jordan, Kuwait, Morocco, Qatar, Britain, Tunisia, Turkey and the European Union.

Monitors say more than 11,000 people have been killed since the uprising against Mr Assad's regime erupted in March 2011, with 127 dying since the truce came into force.

ABC/wires