Charter costs for the biggest tankers hauling Middle East oil to Asia reached this year’s high as demand to book the ships strengthened.

Hire rates for very large crude carriers on the benchmark Saudi Arabia-to-Japan voyage added 8.9 percent to 45.53 industry-standard Worldscale points, figures from the London-based Baltic Exchange showed today. The advance was this year’s biggest and extended May’s climb to 36 percent.

Charter rates on the route to Asia rose 26 percent in a week, according to the exchange’s data. VLCC supply in the Persian Gulf, the world’s biggest cargo-loading region, remained near the “six-month low of 50-something vessels” even as it increased by three to 56 ships, Marex Spectron Group said in an e-mailed report. Each ship can hold 2 million barrels of crude.

“Charterers kept coming into the market on top of each other, and the trend started to firm and rates corrected up,” the consulting unit of Oslo-based shipping-services and investment-banking company Astrup Fearnley said in an e-mailed report today. “The next couple of days/next week will prove if the market has peaked or if there is further upside potential.”

Daily earnings for VLCCs on the benchmark journey climbed 35 percent to $21,802, according to the exchange. Returns surged sixfold since May 22. The exchange’s earnings assessments don’t account for owners’ efforts to improve returns by securing cargoes for return-leg voyages or reducing speed to burn less fuel, the industry’s biggest expense.

The Worldscale system is a way of pricing oil cargoes on thousands of trade routes. Each individual voyage’s flat rate, expressed in dollars a metric ton, is set once a year. Today’s level means hire costs on the benchmark route are 45.53 percent of the nominal Worldscale rate for the voyage.

The advance for VLCCs on the benchmark route was also the largest move among crude tankers tracked by the exchange. The biggest one-day change for vessels shipping refined fuels was for tankers heading to Europe from the U.S. Gulf Coast, which fell 4.3 percent to 80.36 points, bourse data show.