The Ukrainian Insurgent Army (UPA) turned its guns against the Russians after the defeat of the Nazis and were supported by British agents until they were crushed in 1953.

Members of Ukraine's Russian minority and communists condemned the recognition of the fighters who killed tens of thousands of Russian and Ukrainian communists with the help of MI6 and the CIA.

Although it was the largest fighting force to resist the Communists in post-war Europe and fought until 1953, little has been written about it in the West or in Britain whose agents trained, armed and infiltrated the partisans back into Ukraine.

In Ukraine, which emerged in 1991 as Europe's second largest country after the break-up of the Soviet Union, the Communist-era propaganda which labeled the UPA bourgeois nationalists or Nazi collaborators lingered even after independence.

There were calls for the UPA's fight for Ukrainian independence to be officially acknowledged and for members of those organizations to receive the same pensions and other benefits that their compatriots who fought in the Red Army receive.

UPA fighters were overtly anti-Russian and the issue is particularly sensitive as Ukraine walks a tightrope between embracing the West and trying not to offend its huge and powerful northern neighbor.

For years the matter was kept quiet as a historical commission was appointed to explore whether the UPA should be "rehabilitated" and its surviving members be awarded the same pension rights and other privileges enjoyed by Ukraine's Red Army veterans.

But passions flared again after the Ukrainian government said last week it was discussing the rehabilitation of the UPA following the completion of an investigation by the commission.

Russian newspapers launched fierce attacks calling UPA members "bandits" and warning that officially acknowledging the UPA as national heroes will encourage anti-Russian feeling in Ukraine.

The Russian foreign ministry issued a statement about the Kremlin's "negative position" towards any rehabilitation of UPA and Moscow admonished the Ukrainian government for taking the side of the nationalists "instead of reining them in".

Ukrainian foreign minister Anatoly Zlenko responded that "the question of rehabilitation of UPA fighters is an internal matter for Ukraine".

The UPA, formed in 1942, numbered around 100,000 men and women and mostly operated in western Ukraine whose hills, forests and the Carpathian mountains provided excellent cover for the guerrilla fighters.

During the war it fought against the Germans and afterwards, using weapons abandoned by the retreating Nazi forces, fought against Communist forces which were consolidating the westward expansion of the Soviet Union.

Despite facing huge odds UPA became the Russians' most formidable opponent and in the two years after the war killed more than 35,000 of Stalin's NKVD special security forces, predecessors of the KGB.

UPA forces carried out daring ambushes which freed Ukrainians being transported to Soviet prison camps in Siberia and killed top Communist officers sent to combat them, including a Russian Red Army marshall.

The West, fearing a Soviet attack in the Cold War, looked upon the UPA as potential allies and a source of intelligence behind enemy lines.

In an operation codenamed "Integral" Britain's MI6 trained Ukrainian guerrillas and decided that parachute drops were the best way to infiltrate UPA couriers across the heavily patrolled Iron Curtain.

Unfortunately for the Ukrainians one of the MI6 personnel with detailed knowledge about the operation was traitor Kim Philby. Philby, with his friends Donald Maclean, Guy Burgess and Anthony Blunt, was recruited by Russian intelligence in the 1930s at Cambridge University. All went on to join British intelligence and wrought havoc by bet-raying information to Moscow.

During "Operation Integral" Philby was liaison officer for British intelligence with America's CIA, which also covertly helped the Ukrainian cause.

Philby, who later defected to Moscow, and Blunt, alerted Soviet security forces about the planned drops. Dozens of the Ukrainian guerrillas were intercepted and most were executed by the Russians.

The UPA, led by Roman Shukhevych, and operating from bases in forests and an extensive network of secret underground bunkers, battled against Soviet forces and carried out assassinations against Communist officers and officials. The Russians, frustrated at not being able to wipe out the guerrillas carried out vicious reprisals against the civilian population, many of whom were tortured, executed or sent to languish in Soviet prison camps.

Shukhevych saw the UPA, starved of weapons and facing overwhelming odds, was doomed and ordered thousands of his fighters to seek sanctuary in the West. That led to an epic series of battles across central Europe as UPA groups fought against tens of thousands of NKVD troops sent to trap them.

The UPA lost many of their fighters but eluded and destroyed many more of their enemies and made it through to German areas occupied by Britain and the US. Some of those who survived settled in Britain while most made their way to America and Canada.

Shukhevych, who remained in Ukraine, was killed during an ambush by Soviet forces on his command bunker in 1950. Some UPA units continued for a few more years but were broken as a fighting force by 1953.

Thousands of UPAs members were captured and were either executed or spent long years in Siberian prison camps. However, their deeds had passed into folklore and became an important factor in keeping alive Ukrainians' dream for independence.

Askold Krushelnycky