By Ibrahima Sylla

NOUAKCHOTT, Jan 9 (Reuters) - Mauritania will tighten security around its fledgling oil industry following recent attacks by suspected al Qaeda militants on French tourists and government soldiers, its oil minister said on Wednesday.

The Islamic Republic, which straddles black and Arab West Africa, is one of the world's newest oil exploration frontiers although output which started from its offshore Chinguetti field almost two years ago has since been disappointing.

Suspected al Qaeda militants shot dead four French holidaymakers in the south of the country on Dec. 24 and days later killed three army soldiers further north, raising fears of a new campaign.

The Dakar Rally was cancelled for the first time in its 30-year history last week due to security concerns in Mauritania. Its organisers said direct threats had been made against the event by "terrorist organisations".

Oil Minister Mohamed El Moktar Ould Mohamed El Hacen said he was confident the country's oil industry -- including foreign firms exploring its northern desert as well as the off-shore platform -- was safe but said security would be tightened.

"Oil and mining operations have been relatively well secured and we will continue to do so more thoroughly," he told Reuters in an interview.

"In any case there are always army detachments which accompany oil operations in the (northern) Taoudenni basin. There has never been the slightest security incident in these zones," he said.

December's attacks raised concerns that al Qaeda-linked militants behind attacks in Algeria and Morocco may be seeking to extend their operations southwards into sub-Saharan Africa.

The al Qaeda Organisation in the Islamic Maghreb, al Qaeda's wing in north Africa, claimed responsibility for attacks which it said killed four Mauritanian soldiers but did not mention the killing of the French tourists.

Mauritania began pumping oil in February 2006 from its offshore Chinguetti field. Output was initially 75,000 barrels per day (bpd) but has since fallen by four fifths.

Australia's top energy firm Woodside Petroleum Ltd has said it will sell its Mauritania assets, including the Chinguetti field and other offshore development and exploration interests, to Malaysia's Petronas.

Other foreign firms, including Chinese explorers, are prospecting onshore.

El Hacen said he hoped Petronas would improve production at Chinguetti and push ahead with new exploration. But he also said the lower-than-expected production had taught Mauritania not to be overly dependent on oil resources.

"The fall in production has proved to us that you cannot base an economy on oil or mining income. We have to diversify and see this as a contribution to our development," he said. (Writing by Nick Tattersall; Editing by Jon Boyle)