* SA government, security services probing claims
* Junta may be anticipating poll protests
JOHANNESBURG, Nov 18, (Reuters) - South Africa is investigating allegations that some of its citizens acting as mercenaries are training Guinea's military junta, a senior government official said.
Guinea's opposition is demanding the military junta give up the power it seized last December. Tensions have risen since the Sept. 28 killings of opposition protesters in a soccer stadium by security forces, an incident human rights groups described as a pre-planned massacre.
Ayanda Ntsaluba, director general of South Africa's International Relations and Co-operation department, said in a statement late on Tuesday that Pretoria was investigating reports of mercenary involvement.
"The allegation is that there is a group of South African mercenaries training militia largely recruited on an ethnic basis ... and this is relevant with respect to the upcoming elections in Guinea," Ntsaluba said.
South African law -- the Regulation of Foreign Military Assistance Act -- prohibits citizens from fighting for a foreign force without permission from the government.
Elections were due to be held in Guinea in January but observers say they are unlikely to go ahead. Burkina Faso's President Blaise Compaore is leading an international mediation effort but nothing has come from the talks.
The Wall Street Journal, citing an unnamed Western diplomat, reported on Nov. 14 that South African mercenaries are training forces loyal to junta leader Captain Moussa Dadis Camara.
Ntsaluba said information received by the government pointed at South Africans believed to be working with a Dubai-based company involved in training forces loyal to Camara, who has rejected calls to step down since the massacre and has not yet ruled out standing in any election.
"We've heard both true and false leads when it comes to these allegations about mercenaries of South African origin. So we are trying to be cautious, to verify, to validate the information. As I indicated, we are working very closely with our (security) services to try to establish the veracity of this," he said.
Ntsaluba said the military junta seemed to be preparing for a reaction from Guineans if Camara contests the presidential polls.
"The logic of the argument is that that military leadership indeed is determined to avail itself for the presidential elections and also anticipates that there is going to be a reaction from civil society and therefore it's trying to prepare for that eventuality".
Guinea, the world's largest exporter of the aluminium ore bauxite, has faced isolation and punitive measures from African neighbours, the EU and ex-colonial power France since what witnesses said was the killing of over 150 protesters by security forces in the capital Conakry on Sept. 28.
Guinea's opposition is demanding the military junta give up the power it seized following the death of long-time ruler Lansana Conte. But the military rulers have rejected the calls, saying the junta was the victim of plots and they would shrug off sanctions through the nation's mineral weath. (Reporting by Peroshni Govender; Editing by Giles Elgood)