Washington, Mar 9 (IANS): The number of unaccompanied migrant children in US Border Patrol facilities has exceeded 3,200, hitting a new record high, according to internal agency documents.

Among them, some 2,600 were awaiting placement in shelters suitable for minors, but there were just over 500 beds available to accommodate them, Xinhua news agency quoted a CNN report on Monday citing the documents as saying.

Furthermore, nearly 170 unaccompanied children stuck in Border Patrol custody are under the age of 13, according to the documents.

In a statement to CNN, the Department of Health and Human Services said that the Office of Refugee Resettlement "is aggressively working with our interagency partners to ensure that unaccompanied migrant children are safe and unified with family members or other suitable sponsors as quickly and safely as possible.

"The number of unaccompanied children (UC) in our care is constantly changing."

The data reveals the continued bottleneck in the US immigration system, with more migrant children coming into custody than the government is prepared to care for, according to local analysts.