Suspected militants have abducted five oil workers in Nigeria’s restive Niger Delta region, an area regularly hit by militant attacks and abductions.

The militants seized the workers on Wednesday near the Ajoki community, which borders Edo and Delta States, said Delta State police spokesperson, Andrew Aniamaka.

“The police in partnership with the military are working to ensure that the victims are rescued unhurt with the perpetrators arrested and brought to book,” Aniamaka said.

The workers are employees of Sahara Energy Oil Company, a Nigerian energy firm. “They were in a boat en route to an offshore location when the gunmen arrived”, said local resident Ajugu Fidelis, who witnessed the abduction.

“(They) stormed the waterside and ordered the workers into their boat amidst sporadic gunshots and sped off to an unknown location.”

The incident happened a few hours after the Niger Delta Avengers (NDA), a rebel group known to attack oil pipelines, issued a statement warning the government it was ending a 2017 ceasefire agreement.

The NDA’s targeting of oil and gas infrastructure in 2016 led to a slump in output that helped tip Nigeria into recession.

Kidnapping has long been a problem in Nigeria’s southern states where high-profile individuals, including the families of prominent politicians, are regularly seized.