Tomb of the 'Cursed Soldiers': Skeletal remains of young Poles who defended their nation from Hitler and then Stalin are unearthed in mass grave after being killed by Soviet secret police

• The bodies belonged to three victims thought to be around 19-20 years old
• They were found in garden of now-demolished prison in Warsaw
• Was nicknamed 'Toledo' - after sword made in the Spanish city of the same name 

The skeletal remains of teenagers murdered by secret police at a former horror jail run by the Soviet Union have been uncovered in Poland.

The bodies, belonging to three victims thought to be around 19-20 years old, were discovered in the garden of the former prison, in Warsaw, last week.

They were found by investigators searching for victims of Stalin's dreaded NKVD and Communist Poland's Public Security Office.

According to witnesses, Polish political prisoners - resistance fighters who were known as 'Cursed Soldiers' - were buried there after being executed.

Professor Krzysztof Szwagrzyk from Poland's Institute of National Remembrance, which is carrying out the search, said: 'The area we are in still hides many dramatic secrets, and we are here to clear them all up.

'We will do our best to have the whole area examined by the end of this year or the beginning of next year.

'Only then will we be able to say precisely that there are no more human remains.'

The gruesome discovery is the latest uncovered by the institute since it began its research last year.

To date they have uncovered the remains of 20 victims.

Earlier this month, the remains of a man aged 35-45 were discovered, buried without a coffin in a small, unmarked grave.

Opened from 1944 to 1956, the prison was used by the NKVD and the Public Security Office - Communist Poland's secret police - to interrogate, torture and murder resistance fighters opposed to the Soviet regime.

Known as the 'Cursed Soldiers', the Polish soldiers first resisted Nazi occupation of their country.

But as Hitler's forces began to face defeat, the soldiers turned their attention to the growing threat from Stalin and his plans to take over the country.

Hunted down by the secret police, the resistance fighters were either executed on the spot, sent to former concentration and death camps set up by the defeated Nazi occupiers, or jailed in various prisons across the country. 

One of the last members of the Cursed Soldiers to be released from prison was Adam Boryczcka in 1967.

A captain in Poland's underground Home Army and member of the elite British-trained Cichociemny (The Silent and Hidden) intelligence and support group, he was captured and sentenced to death in 1954 after trying to escape Soviet controlled Poland.

Initially set up to fight against the Germans, the 'Silent and Hidden' was a clandestine group collecting intelligence for Britain's secret Special Operations Executive (SOE)  and carrying out key sabotage operations.

Its members later turned their attention to the Soviet threat.

After the fall of communism the convictions of Cursed Soldiers was finally declared invalid and they were annulled by Polish law.

The prison in Warsaw was officially named the Penal and Investigative prison, but, due to its brutality, was unofficially known as 'Toledo' - after the sword made in the Spanish city of the same name.

Surrounded by watchtowers and a 10-foot wall embedded with barbed wire and shards of glass along the top, the former army barracks - which dated back to the time of the Tsar Nicholas II - was the harshest of all Communist interrogation centres. 

Notorious for its torture chambers and the numerous executions carried out in a special death bunker, the bodies were then buried in the grounds and trees planted to cover up the mass graves.

After 1956, 'Toledo' was turned into a prison for women but was demolished in the late 70s to make way for apartment blocks.

The Communist regime in Poland was established in 1952 - after the Soviet Union's takeover of territory from the Nazis' occupation in the Second World War.

As with other countries in the so-called Eastern Bloc - which was made up of East Germany, Czechoslovakia, Hungary, Romania, Bulgaria and Albania - Poland was deemed to be closely tied to the Soviet Union.

A one-party state, the Communist government's rule was characterised by repeated struggles for democracy stoked up by ordinary Poles.