UPDATE 1-Iraq delays Nassiriya oil field decision

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BAGHDAD, May 31 (Reuters) - Iraq has delayed a decision on bids by Japan's Nippon Oil (5001.T: Quote, Profile, Research), Italy's Eni (ENI.MI: Quote, Profile, Research) and Spain's Repsol (REP.MC: Quote, Profile, Research) to develop the Nassiriya oil field, a senior oil official said on Sunday.

The Oil Ministry had been expected to make a decision on the competing bids by the end of May.

"Plans to select one of the offers were delayed as issues relating to contractual terms and some financial aspects of the agreement need more discussion," Deputy Oil Minister Ahmed al-Shamma told Reuters.

Shamma would not say how long the delay might be.

Iraq invited the three companies to compete for the southern field, which officials previously said could pump 100,000 barrels per day within 18 months. Eni executives have estimated it could eventually produce up to 1 million bpd.

The engineering, procurement and construction contract for Nassiriya is one part of the Iraqi government's bid to boost oil production and capitalise on its vast oil resources. (Reporting by Ahmed Rasheed; Editing by Michael Christie and Erica Billingham)