DUSHANBE, Tajikistan ? At least 23 soldiers were killed in Tajikistan after a convoy was ambushed by heavily armed Islamic militants ? a devastating blow that will shake this impoverished nation lying on Afghanistan’s poorly secured northern border.

The military convoy was heading for eastern Rasht district, an area near the border with Afghanistan, when it was attacked in a valley Sunday, Defense Ministry spokesman Faridun Makhmadaliyev said Monday.

The attackers were led by Mullo Abdullo, a radical Islamic commander who came to prominence during the civil war that devastated this former Soviet republic in the 1990s, Makhmadaliyev said.

Abdullo fled to Afghanistan after the end of the civil war in 1997, but he is believed to have returned to his native country some time last year in an effort to overthrow the government led by President Emomali Rakhmon.

Many soldiers were seriously wounded and evacuated for treatment after Sunday’s ambush, Makhmadaliyev said.

The attack comes amid rising tension following a string of terrorist blasts and a large-scale prison escapes by Islamist insurgents and government opponents.

The gunmen are believed to have included citizens from Afghanistan and Pakistan, as well fighters from the volatile southern Russian region of Chechnya, Makhmadaliyev said.

No details were immediately available whether any of the gunmen were killed or captured.

Most Islamist fighters gave up armed resistance after reaching an uneasy peace settlement with the government. But many returned with a hard-line anti-government position over concerns they were being squeezed out of official positions granted to them as part of the peace agreement.

Military activity in the remote and mountainous Rasht Valley, where Abdullo is believed to have taken refuge, has picked up in recent weeks as authorities seek to capture 18 men still on the run after a dramatic prison breakout last month.

Only seven of the 25 fugitives, who included many Islamic militants and government opponents, have been captured.

Sunday’s attack also comes amid rising tension following a series of recent terrorist blasts.

A suicide bombing against a police station in the northern city of Khujand earlier this month claimed two victims and wounded 25. Days later, a bomb was detonated in a disco in the capital, Dushanbe, wounding seven.

Authorities believe Islamic militants were responsible for both bombings.

CIUDAD JUAREZ, Mexico
- Some 200 federal police officers assigned to fighting organized crime in this violent border city detained one of their superiors at gunpoint Saturday to protest alleged corruption.

The protesters complained that the commander, identified as Inspector Salomon Alarcon Olvera, had ordered the detention of another officer who had criticized him. They accused Alarcon of having links to drug cartels and participating in kidnappings, killings and extortion.

The demonstration in front of a hotel that houses some federal police offices led to a confrontation with other policemen supporting the commander. Some blows were thrown, and one injured officer was taken away on a stretcher.

The federal police headquarters in Mexico City said officials from the agency were going to Ciudad Juarez, which sits across the Rio Grande from El Paso, Texas, to hear the protesters’ complaints.

Ciudad Juarez has been the most violent city in Mexico as a result of drug-related violence that has killed more than 28,000 people across the country since President Felipe Calderon ordered a crackdown on cartels in December 2006.

In April, federal police took over public security duties in the city after nearly two years in which the military was primarily responsible for fighting crime.

About 5,000 federal officers are deployed in Ciudad Juarez, which the government says is a battleground between the rival Juarez and Sinaloa drug cartels.

While the officers were protesting, a federal policeman on patrol in another part of the city was slain, Coahuila State Attorney General Arturo Sandoval’s office reported.

Earlier Saturday, authorities aid Mexican marines rescued 12 people who allegedly were kidnapped by an organized crime gang in the northern border state of Nuevo Leon, another of the Mexican regions grappling with drug violence.