Ghana's ministers of defence and environment have died in a military helicopter crash in the central Ashanti region, along with six other people, a government spokesperson says.

Chief of Staff Julius Debrah told a press conference that Defence Minister Edward Omane Boamah and Environment, Science and Technology Minister Ibrahim Murtala Muhammed had been killed in the crash, which he described as a "national tragedy".

Earlier, the Ghana Armed Forces said the aircraft, which was carrying three crew and five passengers had gone "off the radar".

It had taken off from the capital, Accra, at 09:12 local time (and GMT) and was heading to the gold-mining town of Obuasi for a national event.

The authorities have not confirmed the cause of the crash.

The chief of staff has directed the country's flags to fly at half-mast.

He extended condolences to "the servicemen who died in service to the country," on behalf of President John Dramani Mahama and the government.