Esso had to shut down a major pipeline distributing fuel from its Fawley refinery after thieves bored into it and stole a large volume of diesel.
The Midline pipeline was shut down after a tapping device was found inserted into it on April 18 and it resumed operation a week later following repairs and tests.
The pipeline transports fuel from the Fawley Refinery in Hampshire to the Birmingham Fuel Terminal.
The device in the pipeline was discovered near an industrial storage unit at West Wellow, Romsey, in Hampshire, where 30,000 litres of diesel, believed to have been stolen from the pipeline, were recovered.
Hampshire police said two men, both from the Salisbury area, were arrested on suspicion of conspiracy to steal fuel, and have been bailed until July 10, pending further enquiries.