HAMBURG, Oct. 14 -- Argentina has asked an international tribunal to halt an oil project it has no means of stopping on the ground, and the clearest sign of where its pressure is landing comes not from the court but from the project's own operator, which says it is replacing two contractors.

The request, filed on Tuesday with the International Tribunal for the Law of the Sea, asks judges to order the United Kingdom to prevent the start or continuation of the Sea Lion development in what Argentina calls the North Malvinas Basin, the tribunal said in a press release. It rests on arbitration Argentina opened against London on September 28. Until a full arbitral panel is formed, article 290 of the UN Convention on the Law of the Sea lets eit...