MOSCOW - Russia is to free captured killer whales over the next month, but will not return them to their original habitat despite expert advice, a scientist said Wednesday.

The animals will instead be released from their pens in Russia's Far East and may 'disrupt vacationers' at resorts nearby, said Vladislav Rozhnov, who was involved in talks over their fate.

Nearly 100 belugas and orcas were captured last summer and kept in small pens by commercial firms who had planned to deliver them to aquariums, including in China where the industry is booming.

Ten killer whales, or orcas, will be released 'in late May to early June,' Rozhnov said during a briefing at the Russian environment ministry.

He said it would be more ideal to transport them to where they had initially been captured, as Russian and foreign scientists have advised, but this was deemed too costly.

Instead they will be freed in the bay where they have been held near the town of Nakhodka - more than 1,300 kilometers (800 miles) south from where they were actually caught in the Sea of Okhotsk.

There is a risk that the whales will 'stay near the pens where they were fed' and bother humans, he said.

'Science gives recommendations, but the decision is taken by government authorities,' said Rozhnov, who heads the Severtsov Institute of Ecology and Environment and - with other agencies - is part of a council on the fate of the whales.

'We hope that the released animals will go north and return to their native waters,' he said.

Time constraints

The environment ministry said in a statement that transporting the animals to the Sea of Okhotsk could injure the animals and cause stress. Constructing rehabilitation enclosures at a faraway release site would be too complicated, it added.

'Due to constraints of time, the realization of this is difficult,' the ministry said.

Russian officials last month met with U.S.-based conservationists Jean-Michel Cousteau and Charles Vinick, who visited the facility with the killer whales and 87 beluga whales, also captured last year.

Rozhnov said there was no precise decision on the beluga whales, but that scientists now were looking into genetic evidence of family ties between the captured juveniles and known beluga groups in the wild.

'Aggressive' orcas

In a statement Wednesday, Cousteau's team warned that releasing the killer whales near the facility where they were being held carried a 'high number of significant risks.' They included potential conflict with people and boats in the area due to 'aggressive behaviours observed in some of the orcas.'

Such a release 'leads to likely long-term costs and diminished potential for survival,' the team said. They said the whales should be taken to where they were captured following an 'acclimatization period' in remote enclosures.

Russia is the only country still catching wild orcas and belugas. The controversial trade of marine mammals has boomed in recent years together with the aquarium industry in China, which uses Russian animals in its new marine parks.

Although some fisheries officials have defended the capture as a legitimate industry, scientists argue it threatens the species' populations.