Matar Matar, seen here with his family, is known to be a moderate critic of the Bahraini government

A Bahraini court has acquitted a prominent opposition leader who was accused of taking part in "unlawful" anti-government protests that rocked the Gulf state for the last year.

The last of three charges against Matar Matar, a former MP and leading member of Al-Wefaq party, a mainly Shia opposition party, were dropped on Monday by a court in Manama, the capital.

Matar had been charged with "undermining public security by assembling with a group of more than five people".

"The last charge against me has been dropped," he said on Monday,

Bahrain ordered the release in August of Matar and another Al-Wefaq member, Jawad Fayruz, who were both arrested last May after a crackdown on Shia-led protests in the Sunni-ruled country.

The court had already dropped two of the three charges Matar was being tried for: calling for regime change and spreading rumours linked to pro-democracy protests.

Matar and Fayruz were among 18 Shia MPs who resigned in protest at the government's crackdown on the demonstrations that erupted on February 14, 2011. Fayruz's trial is still continuing.

At least 35 people have been killed in the government's crackdown on protests, according to an independent commission of inquiry into the violence.