Anti-government protesters were angered today by a warning from Egypt's vice president Omar Suleiman that unless they joined talks the country could fall to a coup.

His remarks cast a shadow over his efforts to put together negotiations with the opposition over democratic reforms.

The protesters fear the regime will manipulate the talks and conduct only superficial reforms, so they insist they will not enter negotiations until president Hosni Mubarak steps down.

Thousands of protesters chanting "we are not leaving until he leaves" camped overnight in Cairo's Tahrir Square, the centre of their demonstrations.

Many have been sleeping underneath the tanks of soldiers surrounding the square to prevent them from moving or trying to clear the area for traffic.

Tahrir has turned into a giant living room for the protesters, who wake early in the morning to mob the streets, distribute sweets and welcome visitors who come to take pictures with tanks and protesters' banners.

Mr Suleiman's comments the previous night were a blunt, impatient warning for the protests' youth organisers to enter talks and drop their insistence on Mr Mubarak's removal. He rejected any immediate departure for Mr Mubarak - who says he will serve out the rest of his term until September elections - or any "end to the regime."

"We can't bear this for a long time," he said of the Tahrir protests. "There must be an end to this crisis as soon as possible."

He said the regime wanted to resolve the crisis through dialogue, adding, "We don't want to deal with Egyptian society with police tools."

If talks fail the alternative was "that a coup happens, which would mean uncalculated and hasty steps, including lots of irrationalities." The comment appeared to be a possible hint at imposing military law - which would be a dramatic escalation.

Osama Saraya, the editor-in-chief of the pro-government newspaper Al-Ahram , said Mr Suleiman did not only mean a military coup but a takeover by powerful state apparatus or Islamist groups.

But protest supporters and organisers reacted with alarm.

Abdul-Rahman Samir, a spokesman for a coalition of the five main youth groups behind the protests in Tahrir Square, said Mr Suleiman was creating "a disastrous scenario."

"He is threatening to impose martial law, which means everybody in the square will be smashed," he said. "But what would he do with the rest of 70 million Egyptians who will follow us afterward."

Ayman Nour, a former presidential candidate who is an opposition Ghad liberal party leader, dismissed the remarks.

"He is leaving one option to us, since dialogue is not real and those who are talking are Suleiman to Suleiman," he said. "That option is the coup."

Over the weekend, Mr Suleiman held talks with the opposition - including representatives from among the protest activists, the Muslim Brotherhood and official, government-sanctioned opposition parties, which have taken no role in the protests.

But the youth activists have said the session appeared to be an attempt to divide their ranks and they have said they do not trust Suleiman's promises that the regime will carry out constitutional reforms to bring greater democracy in the country Mr Mubarak has ruled for nearly 30 years with an authoritarian hand.

The Muslim Brotherhood, Egypt's largest and best organised opposition group, which initially welcomed the talks, took a tougher line yesterday, calling the regime "illegitimate" and demanding the government open "all files of corruption."