Reliance Industries (RIL) and its foreign partners — the UK's BP and Canada's Niko Resources — have sent a 'notice of arbitration' to the government contesting the Centre's demand of November 3 seeking to recover from them $1.552 billion in the aggregate, for exploiting natural gas that migrated to their KG-D6 block from state-run ONGC 's adjacent asset. Sources confirmed to FE that the notice of more than 20 pages was sent to the petroleum ministry on Friday evening. All the three explorers — RIL, BP and Niko — are signatories in the notice. On November 3, after receiving the government's demand for $1.55 billion, RIL had said that it proposes to invoke the dispute resolution mechanism in the production sharing agreement and issue a notice of arbitration to the government. RIL remains convinced of being able to fully justify and vindicate its position that the government's claim is not sustainable.