FACTBOX: Firms competing in Iraq's first bid round

(Reuters) - Thirty-two of the world's biggest energy companies have qualified and paid to compete in Iraq's first bidding round for oil and gas contracts since the U.S.-led invasion in 2003.

Iraq plans to award eight 20-year service contracts on June 29-30 to boost output at the six oilfields on offer and to develop two gas fields.

The following is the official list of 32 companies competing:

BHP Billiton Marathon

BP Mitsubishi

Chevron Nexen

CNOOC Nippon Oil

CNPC Occidental

ConocoPhillips ONGC

Edison International Petronas

ENI Pertamina

Exxon Mobil Repsol

Hess Royal Dutch Shell

Inpex Sinochem

Japex Sinopec

Gazprom StatoilHydro