Image caption A team of a dozen volunteers visit the cemetery every month

Nature has taken over some of Poland's Jewish cemeteries. But a group of volunteers is trying to ensure those buried in them aren't forgotten.

Alicja Mroczkowska, one of the organisers, hands out gardening gloves. We've a choice of rakes and shears for implements. Alicja says the less energetic ones among us can do the railings. She decants black rustproof paint into small pots.

Our little band of a dozen volunteers heads off into Warsaw's main Jewish cemetery, past the statue of Janusz Korczak - the orphanage director who died at Treblinka after he refused to be parted from the children in his care.

Okopowa Cemetery lies behind a high red-brick wall, right in the centre of the Polish capital.

Image caption Organiser Alicja Mroczkowska brings a team of volunteers to the cemetery every month

Image caption It's thought up to 200,000 bodies may have been buried in the overgrown Okopowa cemetery

But it is a million miles in space and time from the city's slick glass towers and ticking pedestrian crossings. Birds dart between tall acacias and maple trees. Nature has got the upper hand on once-imposing 19th Century sepulchres. In some places, sandstone headstones look like they're drowning in waves of pale green creepers. Time, here, is measured by the speed at which ivy grows.

The cemetery is vast. So far, enough of it has been cleared for 82,000 names to be entered into a database. But up to 200,000 bodies may have been buried here in the past couple of centuries.

One of the volunteers, Karol Sawicki, hacks and rips at weeds that have plaited themselves over a concrete tomb. ''Look at this!'' he says eventually, revealing a marble plaque. ''1942. Sasza Glazman. He died in the ghetto, 32. My age, roughly. I wonder what his story was. We'll never know.''

Image caption The gravestone of Warsaw ghetto resident Sasza Glazman, who died in 1942

There are 1,400 Jewish burial places in Poland. Under restitution laws, these are gradually being returned to the Jewish community. But according to the country's Chief Rabbi Michael Schudrich, there are only 40,000 Jews living in Poland today. There is no money to maintain the graveyards. Hence our little army of plucky volunteers with packed lunches, a wheelie bin and a wheelbarrow.

A white sweat line is edging its way higher and higher up Karol's black cap. We stop for a break. I ask him if he's Jewish. ''I have no idea,'' he says.

"I have my suspicions, like thousands of Poles. My granddad was an orphan. He had three birth certificates with three dates from different villages in Ukraine.''

Image caption Volunteer Karol Sawicki cleared the section around six strangers' graves

Karol is a manager for a children's retail clothing chain. I ask if he takes part in the cemetery clean-ups because of a faint Jewish voice inside himself? ''Maybe. Probably,'' he says.

These are matters that, until recently, were not easily discussed in Poland. The post-war Communist years didn't mark an end to anti-Semitism. The present nationalist government applies so-called "memory politics".

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It's a policy that frames Poland's history around two things - the heroism of Catholics who saved Jews and the wartime deaths of three million non-Jewish Poles. Such a weighty agenda does not leave space for some of the by-products of genocide - collaboration, greed, betrayal - and that which Karol calls ''the kinds of things that go on in all families''.

Monika Siwczyk is painting the crumbling art nouveau railings ringing a grand grave on the principal pathway. ''I love Jewish culture,'' says the 43-year-old professional translator. ''It's missing from Poland today.''

Image caption Volunteer Monika Siwczyk is a keen amateur genealogist

Monika, who is blonde and blue-eyed, has been researching her family's history. She points at her tanned forearm. ''Look at my olive skin. I have found a picture of the sisters of my great, great grandfather. We think they were Jewish. I look so much like them.''

A tram bell rings in the distance. It's a sound I might have heard a hundred years ago, when a third of Warsaw's population was Jewish. A group of tourists walk by. They're speaking Hebrew - young Israelis on a school trip.

''I've chatted to some of them,'' says Karol. ''They are visiting Poland to learn about the Holocaust. It's part of their curriculum.''

Karol would like to see the state of Israel contribute to the survival of Okopowa. ''We can only do so much. Even a ruin needs maintaining. But Israel won't help. Israel wants people to go and live there. It considers Poland to be a closed book - history, finished,'' he says.

The volunteers at central Warsaw's Jewish cemetery are fighting a losing battle against the creeping of time and of ivy. But Karol and Monika aren't discouraged. It's their history, too.

Image caption Student Krystyna Botkina was relieved to find some graves commemorating long life

In just a few hours, Karol has cleared a section of six graves. He's meticulously raked the ground around them.

For a short while, until the weeds grow back, the sun can brighten the blackened concrete tombs of six strangers who died in the ghetto.

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