Opec-member Kuwait has yet to conclude a deal with US major Exxon Mobil Corporation to boost output of heavy crude, but still aims to sign the contract by July, a top Kuwaiti oil official said on Tuesday.

Raising heavy crude capacity is part of Kuwait's plan to increase its output potential to 4 million barrels per day (bpd) from around 2.8 million bpd.

'We are still in the negotiations stage. Until now we have not concluded (a deal),' Sami Al Rushaid, managing director of Kuwait's state-run upstream oil unit, told reporters on the sidelines of a company function.

'We hope to reach it by then,' he replied when asked if the contract would still be signed by July. Kuwait Oil Company (KOC) and Exxon announced in October the preliminary deal for the US firm to help explore and produce oil from the Lower Fars oilfield in the north of the Gulf Arab State.

The two said then they hoped to reach the final deal by July. Political turmoil in the country has led to concern that new oil contract negotiations would be prolonged or delayed.

Any contract would have a performance-related bonus built into it, said Rushaid. 'One of the standards included (in the contract) if we reached a deal to be based on performance or production criteria,' he said, declining to be more specific.

Kuwait is negotiating several service contracts with oil majors to help meet its capacity expansion target. Majors prefer deals that allow them a share of output, but Kuwait bans foreign ownership of its oil and gas reserves.

The performance-related clause in the new contracts it is negotiating aims to keep the majors interested without the Gulf Arab state signing away sovereign rights to its oil and gas.

Kuwait, the world's seventh-largest oil producer, said last year it aimed to produce 50,000 bpd of heavy oil by 2011 and 250,000 bpd by 2015 as part of its plans to boost oil output to 4 million bpd by 2020.-Reuters