There is nothing like a joint cause to help old rivals put aside their differences.Which may be why Chile and Argentina are coming together to oppose British claims over Antarctic territory and seabed. The region is potentially rich in oil and gas but one Chilean member of parliament says his country should not recognise the basis of Britain’s claim. Renan Fuentealba said: “We refuse point blank the pretensions of Great Britain and Northern Ireland of widening their original claims signalled within the Antarctica Treaty and giving them more territory. That is not allowed by the current treaty.” Britain filled a claim under the Law of the Sea to the ocean-bed mineral rights extending off Antarctica. But the Chilean and Argentine politicians hope their meetings will send a clear message to London that some are willing to fight. The Antarctic Treaty of 1961 bans the exploitation for gas and oil in the continent. But the claims must first be approved by a UN commission, which faces a May deadline to announce its decision.