The leader of Bahrain's leading opposition party was hit by a rubber bullet and teargas canister during clashes with riot police on Friday, the party said, describing it as an escalation of government efforts to stop protests led by majority Shiite.
Sheikh Ali Salman was hit on the chest and shoulder, his Wefaq party said in a statement, and several others were also injured including Hassan Marzouk, pictures of whom circulated on social media showing him lying on the ground covered in blood around the neck.
There was no immediate Interior Ministry comment on the incident, but the ministry said late on Thursday it would prevent Wefaq organising a protest in the Sehla district on the edge of the capital.
It said the protest would obstruct traffic and that it had licensed numerous Wefaq protests already this year.
Witnesses said there was a heavy police presence to stop protesters reaching the site. They saw police fire teargas and demonstrators throwing petrol bombs.
"Security forces have been careful in dealing professionally with political leaders but this time was different. It seems a gradual crackdown is going on," said senior Wefaq party member Matar Matar. "They are closing the small margin for freedom of expression."
The Gulf Arab state, which hosts Washington's Fifth Fleet, has been in turmoil since pro-democracy protesters took to the streets in February 2011, after revolts in Egypt and Tunisia.
The ruling Al Khalifa family, which is Sunni Muslim, has extended parliament's powers of scrutiny over ministers and budgets, but rejected demands for full legislative powers and elected governments.
The government says Wefaq and its supporters have a Shiite sectarian agenda. The opposition says this is an excuse to avoid giving up privileges.