A top Muslim Brotherhood leader urged Egyptians to stand ready to sacrifice their lives to prevent a coup, after the army gave Islamist President Mohamed Morsi and his opponents until Wednesday to resolve their differences or face intervention.

"Seeking martyrdom to prevent this coup is what we can offer to the previous martyrs of the revolution," Mohamed al-Beltagui said in a statement on Tuesday.

U.N. leader Ban Ki-moon on Tuesday expressed fear for 2,500 "trapped" civilians as Syrian government forces press a campaign to take the city of Homs, a spokesman said.

Ban renewed a call for a halt to arms supplies to both sides in the conflict as he expressed "grave concern" about the fighting in Homs, said U.N. deputy spokesman Eduardo del Buey.

German Foreign Minister Guido Westerwelle expressed grave concern Tuesday about Egypt's political crisis and urged all sides not to squander the hopes of the democratic revolution.

"I am deeply concerned and I do not want to hide it," he told reporters.

U.N. Secretary General Ban Ki-moon on Tuesday expressed concern about sexual violence used against female protesters in Egypt, where millions have taken to the streets to demand the ouster of President Mohamed Morsi.

"I really hope that while addressing all this current crisis in a peaceful manner, they (Egyptians) should pay more attention to the female demonstrators since we have seen many sexual assault cases over the course of the demonstrations," he told reporters in Reykjavik.

A Tunisian rapper jailed for two years for a song in which he insulted the police will be freed on appeal, to the relief of his supporters who hailed Tuesday's ruling as a victory for freedom of expression.

Ala Yaacoubi, who goes by the rap name Weld El 15, was imprisoned on June 13 for a song he wrote called "The Police are Dogs," and the Tunis court of appeal on Tuesday reduced the jail term to a six-month suspended sentence, allowing him to go free.

At least 14 people were killed in army shelling on a rebel village near the Syrian capital on Tuesday, as violence raged in flashpoint areas of Damascus and in the central city of Homs, a watchdog said.

The shelling comes a day after a powerful car bomb rocked the district of Kafr Sousa in southwest Damascus.

Palestinian president Mahmoud Abbas said on Tuesday that U.S. Secretary of State John Kerry had made "useful and constructive proposals" during his four-day visit last week and said he was "optimistic" about the outcome.

His remarks, at a news conference with visiting Italian Prime Minister Enrico Letta, came in the wake of Kerry's latest attempt to coax Israel and the Palestinians back into direct peace talks, in a visit which the chief Palestinian negotiator said had failed to achieve any breakthrough.

The Jordanian government said on Tuesday that it had blocked 254 unlicensed news websites, 16 of them in the previous two days, using powers under a 2012 law criticized as a threat to freedom of expression.

Fayez Shawabkeh, head of the Press and Publication Department said: "16 local news websites were blocked in the past two days after carefully examining their situation.

A Bahraini court sentenced seven Shiite men to 15 years in prison on Tuesday for the attempted murder of a police officer in August 2012, a judicial source said.

An eighth Shiite was sentenced to three years in prison while two others, on trial over the same case, were acquitted, the source said.

Opponents of Egypt's Mohamed Morsi poured onto the streets of Cairo on Tuesday to press their demand that he step down after the Islamist president snubbed an ultimatum from the army to agree to the "people's demands" or face an imposed solution.

Morsi and army chief Abdel Fattah al-Sisi have been locked in talks all day to "discuss the current crisis," a military source said, as clashes in Cairo between opponents and supporters of the president left seven people dead.