Addis Ababa - Rebel claims that Malaysia's Petronas has stopped oil and gas exploration in Ethiopia are lies and three more firms are in negotiations to start exploration in the country, its mines minister said on Thursday.

Ogaden National Liberation Front (ONLF) separatists and local media said state-owned Petronas had pulled out of the Horn of Africa nation after a gas field it was exploring was overrun by the militants in May.

Petronas have yet to comment on the reports.

The ONLF is fighting for independence for the mainly ethnic-Somali Ogaden and has warned international oil and gas companies to stay away or face attack.

Firms including Petronas and the Vancouver-based Africa Oil Corporation are exploring the Ogaden for potential oil and gas reserves. Twelve foreign mineral firms are exploring Ethiopia for deposits.

Apart from a small discovery of natural gas, which Petronas has signed a $1.9 million deal to extract, Ethiopia has not uncovered significant oil or gas deposits.

The government says the Ogaden basin may contain gas reserves of 4 trillion cubic feet and points to oil-producing neighbours such as Sudan and Yemen as evidence there could be major oil deposits under Ethiopia's vast deserts.