France has urged its nationals to leave Guinea, amid growing criticism of the military junta. There are believed to be some 2,500 French nationals, mainly aid workers, businessmen and their families, in the mineral-rich former French colony. Human rights groups say some 157 people died after troops opened fire on opposition protesters last month. The African Union has told the military leader to step down by Saturday, amid calls for him to be charged. A third civilian minister has resigned from the government in protest at the killings, reports the AFP news agency. On Thursday, the International Criminal Court (ICC) said it had opened a preliminary investigation into the deaths. Human rights groups say soldiers raped and sexually abused women during the crackdown. The military government puts the number of dead at 57 and says most were trampled to death and not shot, as opposition activists say. 'Moral strength' A statement on the French foreign ministry website says that the security situation has worsened since the 28 September protests. "Banditry, in particular armed robberies, have increased and there is no short-term prospect that the situation will improve," the statement says. It says that criminals have been following travellers from the airport and then robbing them when they get home. A foreign ministry spokesman, however, said that there was no prospect of mass evacuation and French expats were being urged to use commercial flights to leave, reports the Reuters news agency. Information Minister Justin Morel Junior said he no longer had the "moral strength to deliver the word of the government", AFP reports. Two other civilian ministers stepped down this week. On Wednesday, European Union development chief Karel de Gucht called for junta leader Captain Moussa Dadis Camara to be tried for crimes against humanity. He said the crackdown on protesters was "an act of brutality never seen before". After the protest Captain Camara pointed the finger of blame at "controllable soldiers", while also saying the opposition should not have held the banned rally. France has already said it will stop weapon sales to the military government. Concern has also been raised over a mining deal which a Guinean minister said had been agreed this week, which could see a Chinese firm pumping $7bn (£4.5bn) into the country. The US-based Human Rights Watch group said the deal "sends the wrong message at the wrong time". "There's a real risk that these investments could entrench and embolden and enrich an already abusive government," the AP news agency quoted HRW's Arvind Ganesan as saying. China has not confirmed the deal, but foreign ministry spokesman Ma Zhaoxu defended continuing trade ties saying the countries shared a "traditional friendship". When Capt Camara took over the country in December 2008, he promised he would not stand in an election he had scheduled for next January. But recently he hinted he would stand, sparking widespread condemnation and opposition protests. Source: BBC