* Protesters breach outer wall of US mission, guards fire warning shots
* Black Islamic flags raised inside German, U.S. compounds
* Crowd smashes property in German embassy, starts fire
* German embassy employees "safe for moment" -foreign minister
KHARTOUM, Sept 14 (Reuters) - Sudanese demonstrators broke into the U.S. and German embassy compounds in Khartoum and raised Islamic flags on Friday in state-backed protests against a film that insults the Prophet Mohammad, witnesses said.
Police armed with tear gas and batons had clashed with protesters for almost an hour but retreated from the front of the embassy after a police car struck a demonstrator and left him on the ground in a pool of blood.
A Reuters witness saw another person lying motionless on the ground nearby but it could not be confirmed whether either man was dead. Sudanese authorities had no immediate comment.
Witnesses said guards inside the U.S. embassy, a vast compound comprising several buildings and tiers of fences, fired warning shots after several protesters clambered over the outer security wall and hoisted a black Islamic flag above a balcony.
Earlier in the day police fired tear gas to try to scatter some 5,000 demonstrators who had surrounded the German embassy and nearby British mission. But a Reuters witness said policemen stood by when the crowd forced its way into Germany's mission.
Protesters raised an Islamic flag saying in white letters "there is no God but God and Mohammed is his prophet". They smashed windows, cameras and furniture in the German complex and then started a fire, witnesses said.
Firefighters arrived to put out the flames.
German embassy staff were safe "for the moment", Foreign Minister Guido Westerwelle said in Berlin. He also told Khartoum's envoy to Berlin that Sudan must protect diplomatic missions on its soil, a foreign ministry statement said.
It was unclear why the two European embassies were singled out since the film was made in the United States, and Muslim outrage has led to crowds assaulting U.S. diplomatic missions in a number of Arab countries.
But Sudan's official body of Islamic scholars had called the night before for a mass protest after Friday prayers over the film and an Islamist group threatened to storm the U.S. embassy.
Sudan has also criticised Germany for allowing a protest last month by right-wing activists carrying a caricatures of the Prophet Mohammad and for Chancellor Angela Merkel giving an award in 2010 to a Danish cartoonist who depicted the Prophet in 2005, triggering demonstrations across the Islamic world.
Sudanese President Omar Hassan al-Bashir has been under pressure from Islamists who feel the government has given up the religious values of his 1989 Islamist coup.
U.S. President Barack Obama's administration said it had nothing to do with the crudely made movie, which inflamed Muslims after it was posted with Arabic subtitles on the Internet, and condemned it as "disgusting and reprehensible".
The film was blamed for an attack on the U.S. consulate in Libya's eastern city of Benghazi that killed the U.S. ambassador and three other Americans on Tuesday, the anniversary of the Sept. 11, 2001 al Qaeda attacks on the United States.