NEW DELHI (Reuters) -Indian state refiners have stopped buying Russian oil in the past week as discounts narrowed this month and U.S. President Donald Trump warned against purchasing oil from Moscow, industry sources said.

India, the world's third-largest oil importer, is the biggest buyer of seaborne Russian crude.

The country's state refiners - Indian Oil Corp, Hindustan Petroleum Corp, Bharat Petroleum Corp and Mangalore Refinery Petrochemical Ltd - have not sought Russian crude in the past week or so, four sources familiar with the refiners' purchase plans told Reuters.

IOC, BPCL, HPCL, MRPL and the federal oil ministry did not immediately respond to Reuters' requests for comment.

The four refiners regularly buy Russian oil on a delivered basis and have turned to spot markets for replacement supply - mostly Middle Eastern grades such as Abu Dhabi's Murban crude and West African oil, sources said.

Private refiners Reliance Industries and Nayara Energy are the biggest Russian oil buyers in India, but state refiners control over 60% of India's overall 5.2 million barrels per day refining capacity.

On July 14, Trump threatened 100% tariffs on countries that buy Russian oil unless Moscow reaches a major peace deal with Ukraine.