Calm returned to the streets of Cairo on Wednesday after demonstrations demanding an end to President Hosni Mubarak's 30-year rule, as protest leaders asked followers to regroup for a second day of action.

Police fired teargas and water cannon in the early hours of Wednesday to disperse protesters who occupied the Egyptian capital's central Tahrir square into the night.

Streets were mostly back to normal by morning, with some shops shut but traffic flowing. Two protesters and one policeman were killed in clashes and protests that erupted on Tuesday in several Egyptian cities, where demonstrators angry at poverty and repression have been inspired by this month's downfall of the leader of Tunisia.

Opposition group Sixth of April Youth movement called on its Facebook page for protests to continue on Wednesday 'and after tomorrow, until Mubarak's departure'.

Security forces said protesters would not be permitted to reassemble. A Reuters witness saw at least 10 riot trucks leaving a Cairo army base in mid-morning.

'Change must happen. It must,' said a butcher in central Cairo who asked to be identified simply as 'an Egyptian'. 'That's life - the old go and the young come with new ideas.'

Police took back control of Tahrir square by dawn after sporadic clashes through the night. Demonstrators had taken over major roads and blocked traffic across the capital.

'Down, Down Hosni Mubarak,' protesters chanted after fleeing from the square in the early morning hours. Some threw stones at police, who charged them with batons to prevent the protesters returning to the square after it was cleared by using teargas.

'Bullies,' fleeing protesters shouted. Others cried: 'You are not men'. Police sprayed a water cannon on protesters and moved in rows into the square.

Washington, a close ally and major donor, called for restraint. Secretary of State Hillary Clinton said Mubarak's government was stable and seeking ways to meet Egyptians' needs.

'The Egyptian government has an important opportunity to be responsive to the aspirations of the Egyptian people and pursue political, economic and social reforms that can improve their lives and help Egypt prosper,' a White House statement said.

Twitter, the Internet messaging service that has been one of the main methods used by demonstrators to organise, said it had been blocked in Egypt.

In a message, the company wrote: 'We believe that the open exchange of info & views benefits societies & helps govts better connect w/ their people.'

Demonstrators on Tuesday tore up pictures of the president and his son, Gamal, who many Egyptians say is being groomed for office. Both Gamal and his father deny any such plan.

As cleaners swept the last debris from central Cairo's streets, state newspaper Al-Masry al-Youm arrived at newsstands with a red, one-word headline: 'Warning'.

'The difference is great between freedom of expression and chaos,' Safwat el-Sherif, the secretary general of the ruling National Democratic Party told state newspaper al-Akhbar.-Reuters