(Corrects spelling of province in paragraph 5)

SANAA, Oct 25 (Reuters) - Sunni al Qaeda militants killed dozens of Yemeni Shi'ite rebels on Saturday in the city of Radda in central Yemen as they pushed back the rebels' advance on the al Qaeda stronghold, tribal sources said.

Shi'ite Houthi rebel forces have advanced into central and western Yemen since they seized control of the country's capital Sanaa on Sept. 21, taking on Sunni tribesmen and al Qaeda militants, who regard the Houthis as heretics.

Fighting has flared in several provinces, alarming neighbour Saudi Arabia, the world's No. 1 oil exporter.

In Radda, in central al-Bayda province, clashes intensified on Tuesday with 30 Houthis and 18 Sunni militants killed in bloody clashes.

On Saturday, al Qaeda fighters surrounded the Houthis on a mountain in Radda at dawn and killed dozens of them and took 12 prisoners forcing them to retreat to Damar province although clashes continued in other parts of the city, tribal sources said.

The Sunni militants seized at least six armoured vehicles and some weapons from the Shi'ite rebels as they retreated, the sources said.

Houthi leaders did not comment on the incident but one leader told Reuters that the reports of what al Qaeda militants grabbed from their fighters were exaggerated.

Radda, with a population of 60,000, has long been a stronghold of al Qaeda, which has drawn many fighters from local tribes who oppose the new presence of the Houthi rebels in the mainly Sunni-populated region.

The northern-based Shi'ite Houthis established themselves as power brokers in Yemen last month by capturing Sanaa against scant resistance from the weak administration of President Abd-Rabbu Mansour Hadi, who appears not to have a full grip on the country's fractious military. (Reporting By Mohammed Ghobari; Writing By Maha El Dahan; Editing by Susan Fenton)

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