“We have not heard anything yet about the two Germans. We have not given up on them, we are still searching for them,” Abia State police spokesman Ali Okechukwu told AFP.

“We are working in conjunction with our counterparts in (nearby) Akwa Ibom State to ensure that we get a useful clue,” he said.

The two Germans – aged 45 and 55 – were kidnapped on Sunday near the Imo river.

The German government had said on Monday that diplomats were working to secure their release.

In Lagos, at the German consulate, the answer was “no news.”

“We are not commenting on such matters,” a diplomat said.

A Nigerian security source said one of the men works in Port Harcourt, the oil city capital of Rivers State, while the other came from Nigeria’s commercial capital of Lagos.

No group has claimed responsibility for the kidnapping.

Okechukwu said that information gathered from locals indicated that the two foreigners came to the river to swim in the company of three young Nigerian women and a driver, but without police escorts.

The kidnappers whisked away the Germans after the swimming while the girls ran into the bush with the driver. The abductors and the Germans headed for Akwa Ibom State, said Okechukwu.

Hundreds of foreigners and locals, mostly oil workers – have been kidnapped since 2006 in Nigeria, mostly in the oil-rich Niger Delta.

Many have been released unharmed, but some only after ransom payments.