LONDON (Reuters) - Oil fell on Monday on worries about renewed tensions between the United States and China, although reports that OPEC and Russia were closer to a deal on extending oil output cuts lent some support to prices.Benchmark Brent crude was down 46 cents, or 1.2%, at $37.38 a barrel at 1331 GMT. U.S. crude fell $1.04, or 2.9%, to $34.45 a barrel.Investors turned cautious after China warned of retaliation on U.S. moves over Hong Kong.Beijing has asked its state-owned firms to halt..