The government "expressed happiness over the release of the state's Director of Budget... and one other person who were kidnapped at gunpoint," the Zamfara state spokesman Yusuf Idris said in a statement.

Officials "commended the victims' friends and all those that negotiated the release," Idris said.

On Sunday gunmen dressed as security personnel kidnapped Zamfara finance minister Hamza Salihu along with two aides and killed his deputy on a highway in neighbouring Kaduna state, a region beset by violence between farmers and herders.

The spokesman did not comment on the fate of the second kidnapped aide and did not say whether ransom was paid for the hostages' release.

The victims were on an official trip when they were ambushed by the gunmen, who also injured a female colleague of Salihu.

Kidnapping attacks have surged in the northwest of Nigeria, the home region of President Muhammadu Buhari.

Criminal groups and bandit gangs -- stealing livestock, kidnapping and destroying villages -- have capitalised on lack of security presence in rural areas.

Entire villages have been deserted for fear of raids by criminal gangs that have made a haven of the dense forest that spreads across northwest Nigeria and into neighbouring Niger.