Seadrill said it had received notice of the claim, which went into effect 3 October, on the semi-submersible West Leo. The company plans to "enforce all its rights as per the contract and governing law", according to a release.

The 2012-built West Leo has been under contract to Tullow since June 2013, with its most recent dayrate at $605,000, according to Seadrill's second-quarter fleet status report.

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