Russian Prime Minister Dmitry Medvedev raised alarm Thursday over immigration to the remote Far East from giant neighbours such as China, saying the region risked falling into foreign hands.

"The objective of defending our Far Eastern territory from an excessive expansion of citizen from neighbouring countries remains," Medvedev told ministers in comments posted on the government's website.

"The Far East really is far away. Not too many people live there, unfortunately."

Russian officials and regional governors have long expressed fears that a population drain in the Far East following the collapse of the Soviet Union could see the region one day fall under Chinese control.

This concern and tough government policies against immigrants have resulted in ethnic conflicts in hubs such as the port city of Vladivostok.

Medvedev, President Vladimir Putin's predecessor and current premier, appeared to be referring to those tensions by urging officials to break up the enclaves of foreigners he said are fast forming in the region.

"It is important to avoid negative manifestations of all types. These include the creation of foreign citizen enclaves," he said. "This is a negative development."

Russia is hoping the region will get a long-term economic boost thanks to billions of dollars spent on basic infrastructure for September's Asia-Pacific Economic Cooperation (APEC) summit outside Vladivostok.

The city's population is estimated to have fallen by about 50,000 since 1991, to just under 600,000 residents in 2010.

Russia's migration service does not report foreign worker numbers in the region.

But local officials and media reports often say the region faces a looming threat from a Chinese population that outnumbers Russians along the Far East border by a factor of more than 10.

Medvedev said eight million foreigners had arrived in Russia in the first half of the year alone and that 10 million migrants were now working in the country.

"We mostly get the poorly qualified workers who can barely express themselves in Russian," said Medvedev. "We have lots of very serious work to do in this respect."