DUBAI: Bahraini police clashed overnight with Shiite demonstrators who took to the streets in protest at jail sentences against prominent opponents, witnesses and the opposition said on Wednesday.

Security forces used tear gas and shotgun fire to disperse masked protesters who burned tyres and rubbish bins at the entrances of Shiite villages west of Manama, and hurled petrol bombs and rocks at security forces, witnesses said.

One protester was seriously wounded in Karrana after receiving a "direct shot in the middle of his body," the main Shiite opposition grouping Al-Wefaq said in a statement.

"Doctors have expressed deep concern over the condition of the wounded man," it said.

The interior ministry said on its Twitter page that a "wounded man was taken to Salmaniya Hospital and that authorities were investigating the situation."

"Your verdicts against our revolutionary figures are unjust!" protesters chanted of an appeal court's decision on Tuesday to uphold jail sentences against 13 leading activists, including seven facing life in prison.

The Sunni-ruled kingdom, home to the US Fifth Fleet and strategically situated across the Gulf from Iran, has continued to witness sporadic Shiite-led demonstrations, mostly outside the capital, since it crushed the protest movement in March last year.

Amnesty International on Tuesday called the verdicts "another blow to justice," adding that they showed "once more that the Bahraini authorities are not on the path of reform but seem rather driven by vindictiveness."