NIAMEY, August 19, 2008 (AFP) - Niger's Court of Appeal Tuesday refused to provisionally release jailed journalist Moussa Kaka, held for the last 11 months for allegedly undermining state security.

The court upheld the state's contention that Kaka, a correspondent for Radio France International, should remain in prison, his lawyer Moussa Coulibaly said.

State prosecutors had lodged a last-minute appeal against his release in June, two days after a senior judge ruled that Kaka had no case to answer and ordered the charges dropped.

'This is a completely unwarranted detention,' lawyer Coulibaly said. 'They are just keeping Moussa Kaka in prison for God only knows what reason.'

Kaka has been held since September 2007 for alleged contact with Tuareg rebels. Human rights watchdogs and press freedom groups have been actively campaigning for his release.

Kaka was alleged to have spoken to the rebels in phone calls which were monitored by the state.

A previous judge -- who was subsequently removed from the case -- in February found that the wiretaps could not be accepted as evidence in court, but the appeal court overruled him.

President Mamadou Tandja's government refuses any dealings with the Tuareg rebels of the Movement of Niger People for Justice (MNJ), which emerged in February last year in the Agadez region of the landlocked, arid west African country and which has since threatened uranium mining there.

RFI was taken off the air in March by the Niger authorities for its support of their journalist, although broadcasts resumed later.

The government has cracked down hard on all journalists believed to have had any dealings with the MNJ.