The Mumbai-Uran Trunk oil pipeline had a small rupture at its termination point last evening, causing an oil spill, a company spokesperson said.
The official had earlier stated the spill occurred in the Arabian Sea, but later corrected it to say that it was at the onland facility and that some oil had flowed into the adjoining sea because of rains last evening.
"The oil leakage has been controlled and control measures have been initiated to deal with the small spill in the sea," the official said.
He said there was power tripping yesterday due to rains, which led to a small leakage developing in the pipeline.
"The SCADA system in the pipeline reported the leak to the control room, which immediately stopped the flow of oil," he said.
The leak was plugged by morning and ONGC teams were using chemicals to control the small quantity of oil floating on the sea surface.
Officials said operations at Mumbai High oil and gas fields remain unaffected and they are producing normally.
The Mumbai-Uran Trunk oil pipeline had ruptured in January 2011, causing a major oil spill 80 km from the Mumbai coast. The spill had spread to around 4 sq km.
In August this year, an oil spill was reported in the coastal areas of Gulf of Khambhat following a rupture in ONGC's pipeline near Bhadbhut village of Bharuch district in Gujarat.