* Sentences comes ahead of Formula one car race
* Bahrain had been rocked by unrest since 2011
* Small kingdom is caught in Saudi-Iran power struggle
MANAMA, March 31 (Reuters) - Thirteen Bahrainis were sentenced to life in prison after they were convicted of trying to kill two policemen by attacking their vehicle and of taking part in an illegal protest, their lawyer said on Monday.
Another man was jailed for 10 years over the same attack and protest - one of a string of clashes that have continued to erupt since mostly Shi'ite Muslims took to the streets in 2011 to demand more say in the Sunni-ruled, Western-allied kingdom.
The sentences, handed out on Sunday, come days ahead of Bahrain's Formula One Grand Prix - an annual event which has been cancelled once, then staged amid heavy security since the demonstrations began.
The island kingdom, home to the U.S. Fifth Fleet, quelled early mass protests with help from forces from neighbouring Sunni power Saudi Arabia.
But sporadic protests have continued and security forces have come under attack from home made bombs. One of three blasts this month killed three policemen, including one from the United Arab Emirates.
Bahrain has accused Shi'ite power Iran of fomenting the unrest. Iran denies having links to Bahrain's opposition or any hand in the violence, but it says it is supportive of Shi'ites there.
Bahraini media said Sunday's defendants were accused of attacking two officers in March 2012 as young men threw Molotov cocktails at police during a protest in the Shi'ite village of Bilad al-Qadeem.
Lawyer Mohammed al-Tajer said he would file an appeal.
"Of course I am going to ask for an appeal. Most of the accused didn't even admit that they committed the crime," Tajer told Reuters, adding that the accused ranged in age from 16-34.
The government had no immediate comment.
Last week, the country's criminal court sentenced 26 Bahrainis to 10 years in jail each for attacking a police station in Sitra in Bahrain's northeast, a defence lawyer said.
Among those convicted was photo journalist Ahmed Humaidan, his lawyer Fadhel al-Sawad said, adding that his client was innocent and had not been present at the scene of the attack and that he would appeal.
Two more Bahrainis were given three-year jail sentences for possessing flammable containers, he said.
Unrest in 2011 forced the cancellation of the annual Grand Prix, but the event went ahead in 2012 and 2013, alongside unrest. The next race is due to take place on April 4-6 .
(Reporting by Farishta Saeed, Writing by Sylvia Westall and Yara Bayoumy, Editing by Sami Aboudi and Andrew Heavens)