Dubai: A homemade bomb exploded in a village in Bahrain on Tuesday, wounding two policemen, the interior ministry said, nine days after another blast in the kingdom killed three police officers.

Bahrain has been grappling with unrest by the Shiite-led opposition over the past three years demanding political reform and an end to perceived discrimination in the country.

Bahrain denies any discrimination against Shiites.

Bomb attacks have increased since last year, raising concern about further instability in the kingdom.

The interior ministry said the two policemen sustained moderate injuries from the bomb as they were working with a third officer to secure a neighbourhood in the village of Al Eker in the late afternoon.

An investigation was under way to identify and arrest those involved in the incident, a statement by the ministry said.

On March 3, three policemen, including one from the UAE, died when what the authorities say was a remote-controlled bomb exploded during a mourning procession for a 23-year-old activist who died in custody on February 26.

The Interior Ministry has said the blast occurred as police were trying to disperse protesters who were blocking roads in the village of Daih, west of the capital Manama. Four people have been arrested in connection to the Daih bombing.

Mainstream opposition groups, including the main Shiite Al Wefaq movement, have condemned the bombing and called on their followers to ensure that protest activities remain peaceful.

The village of Al Eker was the scene of a bomb blast and riots that killed a policeman in 2012, the first to die after the lifting of martial law in the country in June 2011.

Meanwhile, authorities arrested a US national and another individual accused of attacking police in a village.

The two Bahraini suspects, one of whom holds a US passport, were arrested on Monday after they allegedly “demonstrated and attacked a police patrol using Molotov cocktails and iron bars” in the village of Maameer, the public prosecutor said in a statement.

One of them had “a petrol bomb and a bullet-proof vest in his possession,” it added.

They were charged with “taking part in an unauthorised protest, rioting, and possessing petrol bombs,” said the statement.

The lawyer of the suspect carrying a US passport has demanded his release, the statement said, however both “were jailed on remand.”

Bahrain has accused Iran of fomenting bloodshed in the kingdom. Iran denies having links to Bahrain’s opposition or any hand in violence, but champions the cause of Shiites there.