DUBAI, United Arab Emirates — Bahrain’s Parliament approved a constitutional change on Sunday that will allow military courts to try civilians, the kingdom’s latest move in a mounting crackdown on dissent.
Activists warned that the amendment would in effect place the island under an undeclared state of martial law.
Loyalists to Bahrain’s monarchy called the change necessary to combat terrorism, and pointed to sporadic low-level unrest since the Arab Spring protests in 2011 that has recently escalated in tandem with the government crackdown.
Bahrain’s government did not respond to a request for comment about the constitutional change.
But during the council’s session on Sunday, Justice Minister Khalid bin Ali al-Khalifa told lawmakers the amendment was necessary as military judges were “best placed” to deal with “irregular warfare.”
“If militias and armed groups are committing terrorist acts targeting innocent lives and property, as well as receiving elements of combat training, we must confront them,” he said.
Bahrain is off Saudi Arabia’s eastern coast in the Persian Gulf, and hosts the United States Navy’s Fifth Fleet.
The island’s 40-member Consultative Council, the upper house of the Bahrain Parliament appointed by King Hamad bin Isa al-Khalifa, voted for the measure on Sunday.
That approval came less than two weeks after the 40-seat Council of Representatives, the Parliament’s elected lower house, passed it with little opposition.
The bill revises a portion of Bahrain’s Constitution by removing limitations on whom military courts can try.
“This came from the Bahraini king, and for him to sign off on this amendment means that he is personally approving the new repressive measure and all the consequences it will have,” Sayed Alwadaei, the director of advocacy at the Bahrain Institute for Rights and Democracy, said in a statement. “The responsibility for this de facto martial law lies at his feet.”
Bahrain is a predominantly Shiite island ruled by a Sunni monarchy, and is a staunch United States ally.
Government forces, with help from Saudi Arabia and the United Arab Emirates, crushed the 2011 uprising by Shiites and others who sought greater political power.
In the wake of those protests, military courts tried hundreds of defendants.
A government-appointed investigation after the protests criticized the use of the courts, saying they were employed “to punish those in the opposition” and raised “a number of concerns about their conformity with international human rights law.”
Sunday’s vote was the latest in a series of measures to subdue perceived political opponents.
In January, the kingdom restored the power of its feared domestic intelligence agency to make arrests.
Since the beginning of a government crackdown last year, activists have been imprisoned or forced into exile.
Bahrain’s main Shiite opposition group has been dismantled. Independent news gathering on the island also has grown more difficult.
The kingdom has been hit by a series of attacks, including a January prison break. Shiite militant groups have claimed responsibility for some of the assaults.
In January, Bahrain executed three men by firing squad who were found guilty of a deadly bomb attack on police.
Activists said that testimony used against the condemned men had been extracted under torture.
On Saturday, Bahrain accused Iran’s Revolutionary Guard of training and arming some militants.
The executions and mounting crackdown have been linked by activists to the end of President Barack Obama’s administration and the ascent of Donald J. Trump.
Under Mr. Obama, the United States held off on finalizing a multibillion-dollar deal for F-16 fighter jets amid American concerns about human rights abuses in Bahrain.
Since Mr. Trump took office, there has been growing speculation in Washington that the deal might be pushed through.
“In a year where the new Trump administration is dismissing human rights from its foreign policy to Bahrain and the Gulf and preparing to sell arms without conditions, this is a dangerous sign of things to come,” Husain Abdulla, the executive director of the group Americans for Democracy & Human Rights in Bahrain, said in a statement.