Dozens of worshippers kidnapped by gunmen in Nigeria's northern Kaduna state have returned home weeks after their abduction, police have confirmed.

They were among 177 people seized last month from three churches in the remote village of Kurmin Wali.

The 80 people escaped on the day they were taken but hid in neighbouring villages for a fortnight "due to fear of being captured again", state police spokesman Mansur Hassan told the BBC.

The authorities say efforts are ongoing to secure the release of the remaining 86 people still being held. The attack was part of a wave of kidnappings for ransom affecting many parts of Nigeria, but no group has said it was behind the abductions.

The raid was initially denied by police, who only confirmed the kidnappings on 21 January after local residents had reported to the BBC that 177 worshippers were abducted, with 11 escaping shortly afterwards.

The official response drew criticism from Amnesty International, which accused Nigerian authorities of "desperate denial".

The rights group urged officials to "take immediate and concrete measures to prevent rampant abductions that are gradually becoming the norm in Nigeria."

In November, more than 300 students and teachers were taken from a Catholic school in Niger state, which neighbours Kaduna, before being released in two groups.

Nigeria faces multiple, overlapping security challenges beyond kidnappings, including an Islamist insurgency in the north-east, separatist violence in the south-east, and frequent clashes between herders and farmers in central regions over land and water.

Security experts say efforts to tackle these crises are hampered by corruption, poor intelligence sharing, and underfunded local police forces.

The security situation has drawn international attention. In December, the US conducted airstrikes in north-western Nigeria on Christmas Day, targeting two camps run by an Islamist militant group.

Following the action, President Donald Trump warned of further strikes if attacks on Christians in the West African nation continued.

Nigeria, Africa's most populous nation, is home to more than 250 ethnic groups and is roughly divided between a predominantly Muslim north and a largely Christian south, with significant mixing in central regions. 

The government maintains that people of all faiths have been victims of the widespread violence.