Bahrain Mirror- AFP: Authorities in Bahrain said Monday a municipal building was set ablaze as fresh violence erupted over the executions of three Shiites convicted of a deadly bomb attack on police.

Tensions in the Sunni-ruled kingdom have been on the rise since the three men were executed by firing squad on Sunday, a move that drew international condemnation.

The Shiite majority in Bahrain, which has been ruled by the Al-Khalifa dynasty for more than two centuries, has long complained of marginalisation. The country had been rocked by sporadic unrest since 2011.

A municipal building was torched overnight Monday in Shamalia, in the Shiite area of Aali, south of the capital Manama, the interior ministry said, without explicitly linking the incident to the executions.

"According to initial reports, the fire was intentional," the ministry said on Twitter, adding that it had been brought under control.

Protests broke out on Sunday after the executions, reportedly the first carried out in Bahrain in six years.

Demonstrators blocked roads with burning tyres and threw firebombs, and police retaliated by firing tear gas, according to posts on social media.

The confrontations continued overnight, with dozens of men and women marching through the streets of the village of Sanabis chanting slogans against the Al-Khalifa dynasty, according to witnesses.

Demonstrators tried to reach the main street of Sanabis, the hometown of the three executed men, but were blocked by security forces.

- 'Dark day' for Bahrain -

Sanabis was the closest Shiite village to the former Pearl roundabout which was the epicentre of a month-long Shiite-led uprising that the security forces crushed in mid-March 2011.

Protests turned violent overnight in several other Shiite villages, according to other witnesses who said police opened fire with buckshot to disperse demonstrators, wounding several.

Bahrain's authorities do not permit international news agencies to cover events independently.

Bahrain's High Court last week upheld the death sentences against the trio convicted of a bomb attack in March 2014 which killed three policemen, including an officer from the United Arab Emirates.

Seven other defendants received life terms.

The Emirati officer was part of a Saudi-led Gulf force which rolled into Bahrain in March 2011 to help put down the protests.

The executions were criticised by international rights groups, as well as Britain and the European Union.

Shiite-dominated Iran and the Lebanese Shiite movement Hezbollah strongly condemned the executions.

Bahrain is a strategic ally of the United States and home to the US Navy's Fifth Fleet.

It has faced frequent criticism for cracking down on moderate Shiite opposition leaders, including for the jailing of opposition chief Sheikh Ali Salman, who is serving a nine-year sentence.

Authorities have dissolved Salman's Al-Wefaq movement, once the largest bloc in Bahrain's parliament, and repeatedly arrested and detained other opposition leaders, including Nabeel Rajab, the founder of the Bahrain Centre for Human Rights.

Rights group Amnesty International condemned the executions as "a dark day for human rights in Bahrain".

"The fact that this execution was carried out after an unfair trial and despite claims from the men that they were tortured in custody makes this news even more shocking," it said in a statement.