CONAKRY (Reuters) - Security forces in Guinea killed more than 150 people in a crackdown on opponents of military junta leader Captain Moussa Dadis Camara, a local rights group said on Tuesday.

The violence on Monday was the worst since Camara seized power in a 2008 coup and follows months of tension with opponents who demand he honor a longstanding pledge to ensure a transition to civilian rule.

WHAT LED UP TO THE CRACKDOWN?

Opponents believe Camara is preparing to run as a candidate in a presidential election due to have taken place this year but now postponed to January. While he himself has made no formal declaration, his supporters have in recent weeks said there should be no impediment to him standing. Two days after Camara held a rally for his supporters in the city of Labe, a coalition of rival parties sought on Monday to hold their own event at a stadium in the capital Conakry. It was banned but thousands of people took to the streets and broke into the stadium anyway -- prompting an immediate and massive crackdown by security forces.

DOES THIS AUGUR WIDER UNREST?

The violence used by the military on Monday could suggest a deliberate attempt by authorities to dissuade critics from any new challenges to Camara’s rule. Aside from the use of live rounds, eyewitnesses reported gratuitous abuses by soldiers including sexual attacks on women, while media covering the events said they were assaulted by soldiers and their equipment destroyed. Several prominent opposition leaders including Cellou Dalein Diallo of the Union of Democratic Forces of Guinea (UFDG) were arrested on Monday and it is not clear when they can expect to be released. Guinea was quiet on Tuesday, but with the presidential election due on January 31, the country is set for a volatile four months that could spill over into violence at any time.

WHAT IS THE REST OF THE WORLD DOING?

The crackdown brought swift and unequivocal condemnations from United Nations Secretary-General Ban Ki-moon and former colonial power France, which said it would consult with European Union and other partners on what steps to take. The African Union recalled that it had given Camara a deadline of mid-October to confirm he would not be standing in the election or face sanctions. The AU warned that its Commission was already preparing a report on the developments and possible sanctions, but did not elaborate on what moves were possible. The statements amount to concerted external pressure on Camara to relinquish power as promised, but the junta leader has in recent months maintained an openly defiant stance to such calls.

WHAT ABOUT THE ECONOMY?

Camara’s weak point may be his reliance on outside investors to ensure Guinea draws benefit from its huge bauxite reserves. Mining firms such as UC RUSAL and Rio Tinto have not indicated they are ready to leave the country despite a series of disputes. Officials say government revenues from mineral exports is already expected to fall dramatically next year, putting public finances under strain. Analysts believe Guinea’s move to rescind a bauxite refinery deal with RUSAL this month was an attempt by the leadership to apply leverage for better terms on the contract rather than aimed at kicking RUSAL out. For now, investors are staying. But if Camara lets things get out of hand -- either on the streets or in the economy -- they could change their mind.