DHAKA--Bangladesh summoned Myanmar's ambassador on Thursday over an increased security presence near their border, where thousands of Rohingya Muslims have been sheltering just inside Myanmar, Bangladesh's foreign ministry said.

The United Nations refugee agency has expressed concern that thousands of people staying on the strip of land, dubbed "no man’s land" because it is beyond Myanmar’s border fence but on Myanmar’s side of a creek that marks the international border, would be forcibly returned without enough care for their safety.

Nearly 700,000 Rohingya fled Myanmar for Bangladesh after insurgent attacks on Aug. 25 sparked a military crackdown that the United Nations has said amounted to ethnic cleansing, with reports of arson attacks, murder and rape.

About 5,300 people had been staying in a makeshift camp on the border line since late August, but roughly half moved to camps inside Bangladesh after the neighbors met to discuss possible repatriation on Feb. 20.

Several hundred of them have been moved back to the border line, two border guards said.

On Thursday, Myanmar armed soldiers and police, estimated to number more than 200, came to the border fence and appeared to be moving in heavy weapons, including mortars, said a Bangladesh army official and the two guards, all three of whom spoke on condition of anonymity.

Dil Mohammed, a community leader among the roughly 950 Rohingya families staying at the border, said Myanmar officials used loudspeakers to tell them to move from the area.

An official of Bangladesh's border guard said Myanmar security forces fired one round on Thursday evening in an apparent attempt to scare those on the border, but no one was injured.

"It looks like they attempted to push the Rohingya people on the zero line to Bangladesh," Major Iqbal Ahmed said.

PROTEST NOTE

The movement of troops so close to the border violated international norms, another Bangladesh border guard official, Brigadier General Mujibur Rahman, said.

"We are sending them a protest note. We have already asked for a flag meeting," said Rahman, the force's additional director general in charge of operations, referring to a meeting of border guards of both countries.

"They have removed heavy weapons, such as machine guns and mortars, from the area after our verbal protests."

In Dhaka, the foreign ministry said Acting Foreign Secretary Khurshed Alam had asked Myanmar envoy Lwin Oo to ensure that security forces pulled back from the border, as a military build-up would create confusion in Bangladesh and escalate border tension.

The action could also hamper the agreed repatriation of refugees, the ministry said in a statement, adding that it handed a diplomatic note to the ambassador.

A Myanmar official, Myint Thu, on Friday confirmed the ambassador's meeting and said the two countries were "coordinating" on patrolling the border and resolving the issue of those staying there.

Asked about the troop movements, Myint Thu, the permanent secretary at the foreign ministry, said, "This happens due to security concerns."

He did not elaborate, and also declined to comment on whether Myanmar forces fired shots at the border on Thursday.

Myanmar government spokesman Zaw Htay has said "terrorists" with links to the Arakan Rohingya Salvation Army, which had attacked 30 police posts and an army base in August, were sheltering in the border area.

Zaw Htay said he believed people were staying there to put political pressure on the government and "create a situation where Myanmar security forces and government officials will remove them."

There was no plan to collect information on the people in the border area, Win Kyaing, the permanent secretary at Myanmar's immigration ministry, said on Friday, adding that the country had set up two reception centers for returnees.

"They stay there illegally," he said. "They are leaving for Bangladesh in an illegal way."