U.S. Secretary of State John Kerry will visit Egypt a day before deposed Islamist President Mohamed Mursi goes on trial, the next likely flashpoint in the struggle between his Muslim Brotherhood and the army-backed interim government.
Several hundred Islamists protested in a few cities on Friday, responding to a call from a pro-Mursi alliance for daily protests until the ousted president stands trial on Monday.
In Alexandria, seven people were wounded after residents clashed with Mursi supporters before security forces intervened, a security official said. Forty-five Mursi supporters were arrested.
Fighting also erupted in the Gisr al-Suez district of Cairo.
Ties between Washington and strategic ally Cairo have deteriorated since the overthrow of Mursi, Egypt's first democratically elected president.
The state news agency said Kerry's visit to Egypt, the first since Mursi's fall, would only last several hours.
A mass uprising which toppled authoritarian ruler Hosni Mubarak, a longtime U.S. ally, in February 2011 had raised hopes that military men would no longer dominate Egypt.
But the man who removed Mursi, army chief General Abdel Fattah al-Sisi, has become a wildly popular figure and many Egyptians have turned against the Brotherhood and anyone perceived as its supporter, including the United States.
State-run newspapers often carry conspiracy theories which suggest Washington backed the Brotherhood to ensure U.S. domination of Egypt and the rest of the Middle East. One even reported that President Barack Obama is a Brotherhood member.
Those dynamics could make it difficult for Washington to lobby successfully for democracy in Egypt.
In a sign of the tension, the United States said on October 9 it would withhold deliveries of tanks, fighter aircraft, helicopters and missiles, as well as $260 million in cash aid to Egypt, pending progress on democracy and human rights.
Mursi's removal has posed a dilemma for Obama in dealing with a longstanding strategic ally.
He wants to maintain ties with the most populous Arab country, which has a peace treaty with Israel and controls the Suez Canal waterway linking Europe and Asia.
But he does not want to be seen as acquiescing in the ouster of an elected leader, even an Islamist Washington came to view as ineffective during his turbulent year in office.
U.S. PUSH FOR DEMOCRACY
Washington has repeatedly urged the army-backed interim authorities to govern in a more inclusive manner - code for accommodating the Brotherhood and restoring democratic rule.
It has instead taken harsher measures against Egypt's oldest Islamist movement. Hundreds of Islamists have been killed and the Brotherhood's leaders are behind bars, leading to fears that some members of the group will take up arms against the state.
The Brotherhood and its allies have urged crowds to gather on Monday outside a police institute near Cairo's notorious Tora prison, where Mursi's trial is expected to take place.
The charges relate to the deaths of about a dozen people in clashes outside the presidential palace in December after Mursi enraged his opponents with a decree expanding his powers.
Mursi has been held in a secret location since July. In that time Islamist militants have staged almost daily attacks against security forces in the Sinai Peninsula and some fear an Islamist insurgency could spread to other parts of Egypt.
Supporters and opponents of the Brotherhood, which denies any links to militants, have often clashed in the streets.
Egypt has declared a state of emergency and imposed a night-time curfew. A court has outlawed the Brotherhood and ordered its assets seized.
On Thursday the authorities took the unusual step of detaining 21 women Brotherhood members in Alexandria.
Nasser al-Abd, a senior security official in Egypt's second city, said the charges against the women include using force to disrupt traffic during protests, membership of an outlawed group and distributing illegal leaflets.
A lawyer representing the women suspects said they were aged between 15 and 25.
"We are living in oppression and darkness, said Um Yumna, whose daughter was among the detainees. "I can't believe that they made the girls kneel and held up pistols to them. May God avenge this and hurt their hearts like they hurt ours."
Abd, the security official, denied any mistreatment.
Islamists and rights groups accuse the army of staging a coup and returning Egypt to the iron-fisted Mubarak era. The army says it acted in response to mass protests against Mursi and has set out plans for a new constitution and elections.