TOKYO: US Secretary of State Hillary Clinton on Sunday warned that time was running out for the Syrian regime and it needed to start a political transition to save the country from a “catastrophic assault”.

“It should be abundantly clear to those who support the Assad regime their days are numbered,” Clinton told reporters on the sidelines of a conference on Afghanistan in Tokyo.

But she acknowledged that efforts, led by UN-Arab League envoy Kofi Annan, to get the regime of Syrian President Bashar al-Assad to halt its brutal crackdown on the opposition were proving difficult.

Annan himself in an interview with the French daily Le Monde said his six-point plan to end hostilities in Syria had not been successful so far, and there was no guarantee that it would succeed.

Activists say more than 17,000 people have now died since the uprising began in March last year.

“What Kofi Annan said should be a wake-up call to everyone because he acknowledged that there has not been movement by the Syrian regime in accordance with the six-point plan,” Clinton said.

The top US diplomat added: “The sooner there can be an end to the violence and a begetting of a political transition process, not only will fewer people die, but there's a chance to save the Syrian state from a catastrophic assault that would be dangerous not only to the country, but the region.”

Clinton was speaking after attending talks in Paris on Friday in which countries pledged to increase pressure on Assad to step down by seeking a tough UN resolution backed by a threat of sanctions.

She had also met with members of the Syrian opposition leading efforts to topple Assad, whose family has ruled the Arab nation for four decades.

“There's no doubt that the opposition is getting more effective in their defence of themselves and is going on the offence against the Syrian military and the Syrian government's militias,” Clinton told reporters Sunday.

She also pointed to a number of high-level defections, warning the Assad regime that “the sand is running out of the hour glass”.

“We want to make clear to the Syrian regime that they need to be willing to end the violence and start the serious business of a political transition,” Clinton added.