Yemeni warplanes hit Shiite rebel positions in the north for the second day running on Tuesday, after clashes between troops and the insurgents, local and tribal sources said.

The raids targeted positions held by Huthi rebels, also known as Ansarullah, south of Amran city, the sources said.

Fierce clashes first erupted in Amran on Monday after government forces tried to expel rebels from a strategic position controlling the road to Sanaa.

The air force intervened on Tuesday to clear the way for army reinforcements after rebels blocked the way, sources said, reporting casualties but without specifying numbers.

The day before, warplanes had carried out strikes in support of the army and its allies from the Sunni Islah (reform) party against the rebels, local officials said.

Huthis are suspected of trying to expand their sphere of influence as Yemen is split into six regions, pushing out from their mountain strongholds in the far north to areas closer to Sanaa.

The rebels complained Yemen would be divided into rich and poor regions under a federalisation plan agreed in February following national talks as part of a political transition.

Huthis have been fighting the central government for years, complaining of marginalisation under ex-president Ali Abdullah Saleh, who was ousted in a 2012 uprising.

In February, they seized areas of Amran province in fighting with tribes that killed more than 150 people.