(Recasts with release of five foreign hostages, previous ABUJA)

PORT HARCOURT, Nigeria, July 11 (Reuters) - Five foreign oil workers were released in the Niger Delta in southern Nigeria on Wednesday, a week after they were kidnapped on an exploration rig, a police spokesman in southern Bayelsa state said.

Separately, two Nigerians working for Royal Dutch Shell <RDSa.L> in a different area of the delta were also freed, a spokesman for the Nigerian arm of Shell said.

The five expatriates were working for Lonestar, a Nigerian contractor to Shell, on an exploration rig at Soku in Rivers state where they were kidnapped on July 4. They are two New Zealanders, one Australian, one Venezuelan and one Lebanese.

The police spokesman for Bayelsa state, which neighbours Rivers, said the five men had been released unharmed and were now safe in the Bayelsa state capital Yenagoa.

At least 11 other expatriates are still being held by various armed groups in the delta.

The two Nigerians working for Shell were seized on Saturday during an attack on a team repairing a pipeline near the town of Buguma in Rivers.

Kidnappings are extremely frequent in the Niger Delta. Some are carried out by rebel groups seeking to press their demand for local control of oil revenues, but most are the work of ransom seekers.

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