By Edmund Blair and Tamim Elyan
CAIRO, Sept 15 (Reuters) - Clashes near the U.S. Embassy in central Cairo between police and Egyptians incensed over a film denigrating the Prophet Mohammad entered their fourth day early on Saturday, leaving one protester dead and dozens more injured.
The clashes moved to a main road on the banks of the Nile after authorities closed the street leading to the embassy. The protesters, many of whom are intent upon breaking into the embassy, now are seeking alternative routes to the site.
A 35-year-old protester died from bird shot wounds late on Friday, three days after protesters climbed the embassy's walls and tore down the American flag.
"God is Greatest" and "There is no God but God," one group near the front of the clashes chanted as some threw stones on Friday on a street leading from Tahrir Square to the embassy nearby, as police in riot gear fired off rounds of tear gas.
Hundreds of protesters gathered in streets near the mission late into the night, pelting police with stones and petrol bombs as they were pushed back from the embassy perimeter.
The state news agency said 27 people were injured on Friday. Based on figures it announced on other days, that suggested more than 250 people have been injured during clashes this week after Tuesday's breach of the embassy.
"The clashes will continue until President Mursi takes a strong position. ... They aren't for something specific, we are trying to be at the embassy to tell the whole world we are here," said Ahmed Abdel Gawad, 31, who was taking part in the clashes.
President Mohamed Mursi, an Islamist and Egypt's first freely elected leader, has to strike a delicate balance, fulfilling a pledge to protect the embassy of a major aid donor but also delivering a robust line against the film to satisfy his Islamist backers.
In Sinai, militants attacked an international observer base close to the borders of Israel and Gaza, a witness and a security source said. Two Colombian soldiers were wounded, an official from the observer force said.
U.S. Defense Secretary Leon Panetta called his Egyptian counterpart, General Abdel Fattah al-Sisi, on Friday to "underscore the importance of ensuring the safety and security of the U.S. diplomatic mission," Pentagon spokesman George Little said.
"In light of ongoing protests in Egypt, Minister al-Sisi reiterated Egypt's commitment to secure U.S. diplomatic facilities and personnel," Little said.
Many Muslims regard any depiction of the Prophet Mohammad as blasphemous. The low-budget film - produced in California - that portrayed him as a womanizer and religious fake has provoked outrage across the Middle East and led to the storming of several U.S. missions in the region.
Mursi repeated on Friday his condemnation of the film, rejection of violence and promise to protect diplomatic missions in comments in Italy, the second stop of a trip to Europe.
On Thursday, he said he asked U.S. President Barack Obama to act against those seeking to harm relations. His cabinet said Washington was not to blame for the film but urged the United States to take legal action against those insulting religion.
The U.S. government says it had nothing to do with the film but cannot curb the constitutional right to free speech in the United States.
The United States has a large embassy in Cairo, partly because of a vast aid program that began after Egypt signed a peace deal with Israel in 1979. Washington gives $1.3 billion in aid each year to Egypt's army plus additional funds for its government.