FIGHTING

The Brotherhood's political wing called for mass counter- demonstrations to "defend constitutional legitimacy and express their refusal of any coup", raising fears of violence. But the biggest pro-Mursi rally in the a Cairo suburb appeared to attract around 100,000 supporters, Reuters journalists said.

The Brotherhood long avoided direct confrontation with the security forces despite suffering oppression under Mubarak.

The United States, which has previously defended Mursi's legitimacy as a democratically elected leader, stepped up pressure on him to heed the mass protests but stopped short of saying he should step down.

President Barack Obama told Mursi in a phone call late on Monday that the political crisis could only be solved by talks with his opponents, the White House said. Secretary of State John Kerry hammered home the message in a call to his outgoing Egyptian colleague on Tuesday.

That prompted Mursi to say in a tweet that he would not be "dictated to internally or internationally".

At least six ministers who are not Brotherhood members have tendered their resignations since Sunday, including Foreign Minister Mohamed Kamel Amr. The president's two spokesmen and the cabinet spokesman also quit on Tuesday and nearly 150 Egyptian diplomats signed a petition urging Mursi  MORE