A fire at a refinery in Singapore intensified Thursday but was still contained within the offshore site, dpa quoted authorities as saying Thursday. The fire at Royal Dutch Shell\'s Pulau Bukom refinery, five kilometres south-west of the main island, started Wednesday afternoon. There were no major injuries reported. \"The firefighting operations are still ongoing,\" the Civil Defence Force in an updated statement on its website. \"There has been a surge in the fire at the manufacturing facility,\" it said, adding that \"the fire is still contained within the bund wall.\" Cooling operations were being carried out to prevent heat exposure to the nearby storage tanks, it said. Local media reported that three explosions were heard at the site around noon. Shell said \"the fire has now been significantly reduced and is contained to within a bunded area.\" It said refinery units in the vicinity of the fire remained shut down as a precaution. \"We believe it was an accident,\" said Shell. The Bukom site is Shell\'s largest refinery worldwide in terms of crude distillation capacity with 500,000 barrels per day, according to the company website. Around 90 per cent of its production is exported.