Last updated at 18:21 15 July 2007

Russia plunged relations with the West into a new low as President Putin tore up a landmark arms control treaty.

The Kremlin chief's announcement that he was suspending Russia's participation in the Conventional Forces in Europe treaty came as Britain's relations with Moscow are expected to return to the Cold War days of the 1970s this week.

Foreign Secretary David Miliband is expected to announce punitive counter-measures against Moscow over its refusal to hand over former KGB agent Andrei Lugovoi wanted in Britain over the poisoning of Russian dissident Alexander Litvinenko.

It is thought the measures will include the expulsion of Russian diplomats from London in a move that is bound to prompt tit-for-tat expulsions of British officials from Moscow - plunging Britain's relations with the Kremlin to their lowest point since the 1970s and giving new Prime Minister Gordon Brown a major international crisis in his first month in office.

NATO officials have expressed alarm over Russia's sudden withdrawal from the arms control treaty - seen as a warning shot to Washington over President Bush's plans to station missile interceptors in Europe.

"The allies consider this treaty to be an important cornerstone of European stability and they would like to see it ratified as soon as possible," a NATO spokesman said.

"NATO regrets this decision by the Russian Federation. It is a step in the wrong direction," he added.

He said the treaty had boosted stability in Europe by providing unprecedented transparency in military matters on the continent.

NATO officials said the treaty called for a 150-day notice period before any member could withdraw, and that it remained unclear whether Moscow had invoked that provision.

The CFE was signed in 1990 and extensively amended in 1999 to reflect changes created by the disintegration of the Soviet Union, and the fact that many former Warsaw Pact allies of the U.S.S.R. had by then joined the North Atlantic Treaty Organization.

It added the requirement that Moscow withdraw troops from the former Soviet republics of Moldova and Georgia. Russia ratified the amended version, but the United States and other NATO members have refused to do so.

Russian troops have since left Georgia, although some of their equipment remains to be repatriated. But Moscow has refused to withdraw its troops from Moldova's breakaway Trans-Dniester province, saying they are there as peacekeepers preventing a resumption of hostilities between the two sides.

Still, NATO nations have insisted that because Moscow did not have "host nation consent" from Moldova, it should withdraw its forces from the region.

President Vladimir Putin signed a decree at the weekend freezing Russia's participation in the Conventional Forces in Europe Treaty, citing "extraordinary circumstances ... which affect the security of the Russian Federation and require immediate measures," the Kremlin said in a statement.

Russia in the West are already at odds over U.S. plans to build a radar site in the Czech Republic and missile interceptors in Poland, Russia's conflicts with its neighbors, including Georgia and Estonia, and Western criticism of Russia's democracy and human rights record.

Kremlin spokesman Dmitry Peskov said Russia could no longer tolerate a situation where it was complying with the treaty but its partners were not, and he expressed hope Russia's move would induce Western nations to ratify the updated treaty.

The White House said it regretted the Kremlin's move.

"We're disappointed Russia has suspended its participation for now, but we'll continue to have discussions with them in the coming months on the best way to proceed in this area - that is in the interest of all parties involved and provides for security in Europe," the U.S. National Security Council said in a statement.

Withdrawal from the treaty would allow Moscow to build up forces near its borders. But Russian military analysts have said Russia's move was a symbolic raising of the ante in the missile shield showdown more than a sign of impending military escalation.

Russian officials have staunchly protested U.S. missile plans, saying the U.S. system is aimed at its nuclear arsenal, and would upset the balance of strategic forces in Europe.

The U.S. insists that the anti-missile system is aimed at future nuclear threats from Iran.