Limited rail capacity and poor port infrastructure are frustrating the ambitions of the country's leading coal producers to increase exports quickly to make up for weak domestic demand during the recession.

Industry executives and experts told last week's Adam Smith CIS Coal Summit that state-controlled transport costs remained too high and years of underinvestment were taking a toll on shipping and rail links.

For Alexander Kovalchuk, director of the Coal Market Research Institute, the problem is shown by bottlenecks at SUEK's new Vanino coal terminal in the Far East, which began handling shipments for the company, Russia's largest coal producer, in December.

"Vanino suffers a lot because the [Baikal-Amur Mainline] railway doesn't have sufficient capacity; it is underserved by 40 to 50 percent, according to SUEK estimates," Kovalchuk said.

Exports are becoming increasingly attractive to both steam and coking coal producers as China and India continue growing their economies while Russian industry sputters.

Market players estimate Russia exported 7.2 million tons of coal in April, compared with 7.5 million tons a year ago.Overall Russian coal production declined by about 13 percent in April.

Raspadskaya deputy director Alexander Andreyev said his firm exported 35 percent of coking coal output in April, up from the 26 percent average in the first quarter. "We need to change our strategy by expanding exports step by step," he said.

For Russian producers to expand their share of the Asian market in the long term, experts say more investment is needed by Russian Railways together with lower tariffs for coal shipped more than 5,000 kilometers from Siberia to ports in the Far East.