OPEC member state Kuwait has stepped up security to the highest level at state-run oil conglomerate Kuwait Petroleum Corp (KPC) and its affiliates, state-run KUNA reported on Saturday, a day after a suicide bomber killed 27 people in a Shi'ite mosque.

KUNA quoted Sheikh Talal al-Khaled al-Sabah, spokesman for the country's oil sector.

Separately, state-run oil refiner Kuwait National Petroleum Company (KNPC) said "extra monitoring and searches" were being taken to increase security.