Sept. 3 (Bloomberg) – A surplus of supertankers competing to ship 2 million-barrel cargoes of Middle East oil to Asia swelled as demand slowed, increasing pressure on owners as fuel costs rise.

There are 30 percent more very large crude carriers, or VLCCs, for hire over the next 30 days than there are cargoes, according to the median estimate of five ship brokers and two owners surveyed by Bloomberg News today. On Aug. 24, the surplus was 18 percent.

Slower-than-expected vessel demand caused the increase, said Halvor Ellefsen, a tanker broker at SeaLeague A/S in Oslo.

Tanker owners are contending with a VLCC fleet that’s expanded by 5.6 percent to 527 vessels this year even as Middle East producers in the Organization of Petroleum Exporting Countries cut crude output. Ship-fuel prices have more than doubled to $429 a metric ton at Rotterdam this year, further lowering owners’ returns from leasing their vessels.

The benchmark tanker rate, based on Saudi Arabian shipments to Japan, fell 0.03 percent to 30.77 Worldscale points today after sliding 20 percent in the five days to Aug. 28, its biggest weekly drop since July 7, according to data from the London-based Baltic Exchange. Returns from the voyage are $1,358 a day, about $10,000 a day less than London-based Drewry Shipping Consultants Ltd. estimates owners need to pay crew, insurance, repairs and other running costs.

Five of the seven respondents said the supply of VLCCs expanded relative to demand, compared with their last estimates. Two said it shrank.

The carrying capacity of the VLCC fleet has increased by about 9.2 million deadweight tons, or 6.2 percent, to 156.8 million tons this year, according to Lloyd’s Register-Fairplay data on Bloomberg. Over the same period, Middle East producers in OPEC cut their combined output by 3.6 percent to 19.3 million barrels a day, according to Bloomberg estimates.