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JOS, Nigeria, Sept 19 (Reuters) - The suspected leader of Nigeria's main militant group in the oil-producing Niger Delta has been taken to a hospital for medical treatment, a defence lawyer said on Friday.

A trial court judge ordered state security officers to take Henry Okah, who is in jail for gun-running and treason, to an undisclosed hospital after defence lawyers said he was suffering from "kidney complications," said Femi Falana, one of Okah's lawyers.

The federal judge adjourned Okah's hearing for Oct. 3 after prosecutors agreed to submit witness statements and evidence to Okah's defence team.

Okah, believed to be the leader of the Movement for the Emancipation of the Niger Delta (MEND), still commands loyalty from several well-armed factions in the delta. He could face the death penalty if convicted.

MEND, which declared an "oil war" against the oil sector and military this week, is holding three foreigners and 22 Nigerian oil workers captive as leverage for Okah's release. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ ) (Reporting by Shuaibu Mohammed; Writing by Randy Fabi; Editing by Tume Ahemba and Ralph Boulton)

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