The Iraqi oil ministry and OAO Lukoil Holdings (LKOH.RS) Thursday signed an amended contract to cut the production target from Iraq 's West Qurna-2 oil field 33%, a senior Iraqi oil official said Thursday.

Abdul Mahdy al-Ameedi said the target for West Qurna-2, operated by Lukoil, is reduced to 1.2 million barrels a day instead of the previously agreed 1.8 million barrels a day.

Lukoil, Russia's biggest privately-owned oil producer, would operate the field for 25 years instead of the 20 years projected earlier, Mr. Ameedi said, adding that the revision also prolongs the production plateau period to 19.5 years from the 13 years agreed upon earlier.

But the amended contract hasn't changed the time limit for reaching the production plateau rate of 1.2 million barrels a day by the end of 2017.

Lukoil Chief Executive Vagit Alekperov signed the amended contract for West Qurna-2 oil field in
Baghdad Thursday, the company said in a statement.

Mr. Ameedi said the reasons that have led
Iraq to reduce output from West Qurna-2 and other Iraqi fields include, among others, poor infrastructure, a predicted slump in world oil demand, high costs of building production facilities and potentially lower oil prices due to high production.

The oil ministry is also planning to reduce production plateau rates from other southern oil fields, such as Majnoon, Rumaila, West Qurna-1 and Zubair, which are operated by Royal Dutch Shell PLC (RDSA), BP PLC (BP), Exxon Mobil Corp. (XOM) and Eni SpA (E), respectively, he said.

"We are also going to amend contracts of these fields during a month or two," Mr. Ameedi said, without giving further details.

First production of 150,000 barrels a day from West Qurna-2 is expected in November this year, according to Lukoil officials, and is expected to increase to 500,000 barrels a day in 2014.

The company has increased its stake in the West Qurna-2 project in
Iraq to 75%, following last year's withdrawal of Norwegian oil company Statoil ASA (STO), which used to own 18.75% in the project. Iraq 's state-owned North Oil Company owns 25%. This has been fixed in the amended contract, Mr. Ameedi said.

Lukoil will invest $30 billion to upgrade the field, Sergey Nikiforov, senior vice president for development and production at Lukoil Overseas Holding Ltd., said at a ceremony held in the field last year.

Operator Lukoil and Statoil were awarded a 20-year service contract at West Qurna-2 in December 2009. The pair promised to get the field pumping at 1.8 million barrels a day for payment of $1.15 a barrel.