BOSTON -- Three Afghanistan National Army officers who vanished during training in Massachusetts were placed in the custody of U.S. Immigration and Customs Enforcement on Tuesday after being detained on the Canadian border, authorities said.

The agency said the officers faced removal proceedings after being charged with administrative immigration violations. A spokesman for the agency said he could not provide more details on the charges.

The men were being held at the Buffalo Federal Detention Facility in Batavia, New York, according to ICE's online detainee locator.

The Massachusetts National Guard said earlier that the Afghan soldiers, identified as Maj. Jan Mohammad Arash, Capt. Mohammad Nasir Askarzada and Capt. Noorullah Aminyar, had been detained by the Canadian Border Security Agency on Monday as they tried to enter Canada on the Rainbow Bridge, which connects New York and Ontario at Niagara Falls.

Military officials said the men had been participating along with officers from Tajikistan, Pakistan, Kazakhstan and Mongolia in a U.S. Central Command Regional Cooperation training exercise at Joint Base Cape Cod. They were reported missing Saturday after leaving Camp Edwards on an off day to visit a shopping mall.

The exercises, scheduled to end Wednesday, have been held annually since 2004 to promote co-operation and interoperability among forces, build functional capacity, practice peacekeeping operations and enhance readiness, officials said.

U.S. authorities have stressed that they do not believe the men posed any danger to the public. Massachusetts Gov. Deval Patrick, who had been briefed over the weekend, said on Monday the soldiers had been fully vetted before entering the U.S., adding there was speculation within the military that they might be seeking to defect.