KUWAIT (Reuters) – Kuwait will finish cleaning up a crude oil spill in the country’s southern waters in the Gulf this week, a Kuwaiti newspaper report said on Sunday, quoting the country’s oil minister.

Essam al-Marzouq told the al-Rai newspaper that no more patches of oil have been found and that Kuwait was working on clearing up those near the shore. He did not give a reason for the spill.

On Saturday Kuwait said various services were investigating the incident but did not give the magnitude of the spill near Kuwait’s southern Ras al-Zour area nor its cause.

Ras al-Zour is where Kuwait National Petroleum Company (KNPC) is building the Middle East’s largest oil refinery, with a processing capacity of 615,000 barrels per day and $11.5 billion worth of contracts.

Saudi Arabia and Kuwait jointly operate fields in a shared area known as the Neutral Zone.

The Khajfi Joint Operations (KJO) said in a statement on the Saudi Press Agency early on Sunday that its facilities were safe and were clear of a spill “which (media) reports said was due to an oil tanker.”

The KJO, which is a JV between Kuwait Gulf Oil Co and AGOC, a subsidiary of Saudi state firm Saudi Aramco added that it put an emergency plan into effect to deal with the spill and it will conduct an aerial survey of the area to make sure the facilities and beaches were safe.

The Khafji oilfield was shut in October 2014 for environmental reasons and Wafra has been shut since May 2015 due to operating difficulties.