By Aaron Maasho

ADDIS ABABA, April 1 (Reuters) - An Ethiopian opposition group said on Friday that police had arrested more than 2,600 people in the last three weeks for taking part in land protests and that the government was thereby aiming to deter future protests.

Plans to requisition farmland in the Oromiya region surrounding the capital for development sparked the country's worst unrest in over a decade, with rights groups and U.S.-based dissidents saying as many as 200 people may have been killed.

An opposition coalition said the arrests over protests in the four months up to February came despite government assurances of clemency.

Representatives of the government were not immediately available for comment.

Authorities scrapped the land scheme in January and pledged not to prosecute the demonstrators, while Prime Minister Hailemariam Desalegn issued an apology in parliament last month saying his administration would work to address grievances over governance.

Despite the pledges, the Ethiopian Federal Democratic Unity Forum (MEDREK) said 2,627 people have since been "illegally rounded up" and remain under custody.

"It is an act of reprisal," MEDREK's chairman Beyene Petros told Reuters.

"The whole purpose why they are increasing their witchhunt is to simply stop the public from planning or initiating any future public protest," he added.

The coalition said in a statement that the arrests took place in 12 different areas of Oromiya, Ethiopia's largest region by size and population.

The second-most populous nation in Africa with 90 million people, Ethiopia has long been one of the poorest countries in the world per capita, but has made strides toward industrialisation, recording some of the continent's strongest economic growth rates for a decade.

But reallocating land for new developments is a thorny issue in a country where the vast majority of the population still survives on small farms. The opposition says farmers have often been forced off land and poorly compensated. (Reporting by Aaron Maasho; Editing by Hugh Lawson)

(Adds name of target, paragraphs 2-4)

WASHINGTON, April 1 (Reuters) - The U.S. military has carried out an air strike against a senior leader of the al Qaeda-linked militant group al Shabaab in Somalia, the Pentagon said on Friday.

The results of the air strike, which was carried out on Thursday, were still being assessed, it said.

The target of the operation, Hassan Ali Dhoore, played a direct role in al Shabaab's Christmas Day 2014 attack on the Mogadishu airport in which one American was among those killed and an attack on a Mogadishu hotel in 2015 that killed 15 people, including a Somali-American, the Pentagon said.

"Removing Dhoore from the battlefield would be a significant blow to al-Shabaab's operational planning and ability to conduct attacks against the government of the Federal Republic of Somalia, its citizens, U.S. partners in the region, and against Americans abroad," the Pentagon said in a statement.

The strike came weeks after the United States targeted an al Shabaab training camp in Somalia in an air strike that the Pentagon says killed more than 150 fighters.

That operation, using both manned aircraft and unmanned MQ-9 Reaper drones, targeted al Shabaab's "Raso" training camp, a facility about 120 miles (190 km) north of the capital Mogadishu.

Al Shabaab was pushed out of Mogadishu by African Union peacekeeping forces in 2011 but has remained a potent antagonist in Somalia, launching frequent attacks in its bid to overthrow the Western-backed government.

The group, whose name means "The Youth," seeks to impose its strict version of sharia law in Somalia, where it frequently unleashes attacks targeting security and government targets, as well as hotels and restaurants in the capital.

Al Shabaab has also been behind deadly attacks in Kenya and Uganda, which both contribute troops to an African Union peacekeeping force in Somalia. (Reporting by Phil Stewart; Additional reporting by Eric Beech; Editing by G Crosse, David Gregorio and Mohammad Zargham)