Nigeria's government has secured the release of 100 schoolchildren who were abducted last month in Niger state in one of the country's worst mass kidnappings to date, local broadcaster Channels Television reported on Sunday.

The Christian Association of Nigeria (CAN) has said that 12 school staff were kidnapped on November 21 by gunmen at St. Mary's Catholic boarding school in Papiri, a hamlet in Niger state.

Fifty pupils managed to in the following hours, but since then there had been no update on the whereabouts or conditions of the other children, some as young as six, and the missing school staff.

Channels Television did not immediately provide details about the release.

The CAN and Niger state authorities said they were not officially notified of the release of the children.

The Nigerian government did not immediately comment.

"We are not officially aware and have not been duly notified by the federal government. We hope and pray it’s true and will be looking forward to when the remaining will be released," said Daniel Atori, spokesperson for the head of CAN in Niger state.

The school attack put a spotlight on the persistent in Nigeria more than 10 years after the Chibok mass abductions, at a time when the country is under scrutiny from U.S. President Donald over its alleged ill-treatment of Christians.

Earlier on Sunday, a U.S. congressional delegation met with Nigeria's national security adviser Nuhu Ribadu in Abuja, where "discussions focused on counter-terrorism cooperation, regional stability and strengthening Nigeria-U.S. security partnership," Ribadu said.