LONDON, Oct 3 (Reuters) - Swiss-based commodities trading house Gunvor Group said on Monday it had secured $500 million in loans to support its newly established energy operations in Houston in the United States.

The company said its U.S. team would initially trade refined products, natural gas and bitumen.

In spite of the weakness in the oil price this year, Gunvor has managed to secure funding for its operations. In August, it raised $200 million in project financing to upgrade its 88,000 barrel per day Rotterdam oil refinery.

A weaker oil price tends to be a boon to refiners, who can profit from more generous refining margins.

In May, Gunvor Group closed a syndicated revolving credit facility of $1.04 billion to fund new and existing operations in the Asia Pacific region.

The loan was initially launched at $750 million but was increased after being heavily oversubscribed.

Gunvor, which reported a rise in trading volumes to 180 million tonnes in 2015 from 137 million tonnes the year before, is one of the world's largest commodity traders. (Reporting by Amanda Cooper; editing by David Clarke)