Crude production from the Khafji oilfield, jointly run by Saudi Arabia and Kuwait, has been halted temporarily to comply with environmental rules, according to an industry source familiar with Saudi policy and an internal letter seen by Reuters.

The move is unlikely to affect oil supplies from Saudi Arabia, the world's top oil exporter, because of the kingdom's significant crude output capacity, currently at 12.5 million barrels per day (bpd). In September, Saudi pumped 9.704 million bpd.

But it adds to a long list of disruptions in projects between the two neighbouring Opec members, hampering oil and gas exploration and production from shared fields.

The Khafji field, whose production is around 280,000 bpd to 300,000 bpd in the Neutral Zone between Saudi and Kuwait, was to be brought offline "immediately", according to a letter signed by Abdullah Al-Helal, chairman of Aramco Gulf Operations (AGOC), which operates the Saudi part of the field.

The industry source told Reuters on Sunday the shut down had already taken effect and it was not immediately clear how long it would take to bring it back online after complying with the environmental regulations.

Al-Helal could not be reached for comment and senior Kuwaiti oil officials did not respond to a request for comment.

Al-Khafji Joint Operations Company (KJO) is a joint venture between AGOC, a subsidiary of state oil firm Saudi Aramco, and Kuwait Gulf Oil Company (KGOC).

In the letter, dated October 16 and addressed to Mohammed Al-Khatib, executive director of operations of KJO, Al-Helal referred to non-compliance with new environmental air emission standards issued recently by Saudi Arabia's Presidency of Meteorology and Environment Authority.

"The Khafji issue is purely environmental," said the industry source familiar with Saudi oil policy. He said Aramco and all other companies operating in the kingdom have to comply with orders issued by Saudi's PME Authority.

Other sources told Reuters an onshore gas gathering plant in Khafji needed to be repaired after a gas leak and that the repairs could take around six weeks.

"The Kuwaitis have refused to allow a shutdown for repairs because of their gas shortfall during the summer. This has been an escalating confrontation between Kuwait and Saudi Arabia," one of the sources said.

"The plant gathers the gas from all onshore facilities in the Neutral Zone and therefore the whole area requires a shutdown during the repairs unless the gas is flared during the entire turnaround," the source added.  - Reuters