An uncontrolled flow of gas from the `B-121-D' well, connected to the B-121 platform comprising five wells which began at 0930 hours on Thursday, caught fire just after noon on Friday, an ONGC spokesman said in a statement.

Three multi-support vessels--Samudra Sevak, Stenna I and Stenna II--were put into service on Thursday and are spraying water on the burning well to prevent the fire from spreading, he said.

Two experts from Cudd Well Control Company, an international well control and fire control company, have been summoned and are expected to arrive here on Saturday.

ONGC senior executives led by director (operations) AS Soni, executive director VK Sharma and chief general manager (operations) Gyan Singh have rushed to the site and a further action plan will be charted out accordingly, the spokesman said.

ONGChas set up a control room for round-the-clock monitoring of the incident.

ONGC said all the 85 crew members on the rig Sagar Ratna, which was deployed for "work-over" operations, have been evacuated to safety.

The B-121 platform was shut down for maintenance work undertaken about 20 days back. The platform produces two million cubic metres of gas per day.