Bahraini authorities said a policeman has been killed in a "terrorist" attack using a bombing provided by Hezbollah.
The explosion took place in the village of Damistan, around 20km southwest of the capital Manama, late on Monday, killing an on-duty policeman, the interior ministry said on Twitter.
Bahrain's Foreign Minister, Sheikh Khaled bin Ahmed al-Khalifa, said the policeman died of wounds caused by "a bomb made by the terrorist Hezbollah" group.
He was referring to the Lebanese Shia armed group, which Bahrain has previously accused of being linked to Shia armed groups in the country.
The Sunni Muslim-ruled island kingdom, has accused the the Hezbollah and neighbouring Iran of fomenting unrest in the kingdom, a charge that both have repeatedly denied.
Home to the US Fifth Fleet, Bahrain was swept by protests in 2011 led by the majority Shia community demanding political reforms.
The tiny gulf kingdom remains deeply divided three years on, with a growing number of attacks using improvised explosives and anti-government protesters frequently clashing with police.
In March, three policemen were killed by a remotely-detonated bomb. Two policemen were injured last month by a bomb in the Shia village of Deraz west of Manama.
Scores of Shia protesters have been jailed on "terrorism" charges with human rights groups accusing Bahrain of stifling freedom of expression in the country.