Nina Nikiforovna, a pensioner in the rebel-held city of Donetsk in eastern Ukraine, took up begging recently.

"I never thought I'd live long enough to know such shame," she says, but she needs pills for her heart condition and after several months without receiving her pension, she saw no alternative.

Hundreds of thousands of pensioners in the pro-Russian east of Ukraine, already caught up in seven months of conflict between government and rebel forces, have lost their only source of income.

This month, the government in Kiev officially cut off rebel-held areas from all financial support, including welfare payments and pensions. Then they stopped postal and banking services.

"With this decision, the Ukrainian authorities have made a difficult situation even worse," said Evgeny Shibalov, a charity volunteer that helps distribute aid to people in the region.

Most of the 650,000 pensioners in these areas have not received any money from the government since August.

But the new rules mean they must now produce papers saying they have left the rebel zone and live in a government-controlled area.

That has quickly bred a rash of corrupt middle men offering fake residency documents. The going rate is around 500 hryvnias (25 euros, $31) -- a sizable chunk out of a monthly pension of just 1,670 hryvnias.

"It's already been over a month since I went to Kramatorsk to try to get the documents for my pension. And now, I have to queue again in the cold and I'm not sure anything will come of it," said Ekaterina Savenko, 70.

She was one of around a hundred people queuing outside Donetsk railway station on a recent morning, hoping to get hold of a ticket and then reach somewhere where she could buy papers proving she was internally displaced.

Newly confirmed prime minister Arseniy Yatsenyuk places the blame for this "humanitarian catastrophe" squarely at the Kremlin's door -- saying Russia has fomented and supported the separatist uprising in the east.

But that is little consolation to the thousands who are housebound or lack the money to travel outside rebel areas.

"Just in Donetsk, there are nearly 30,000 people who can't move or get any help from their families. Many are lacking the most essential medicines. They find themselves today on the edge of survival," said Shibalov, the charity worker.

The government says no one has died of hunger on its watch, but it has no figures for what is happening in rebel areas.

Up to now, most have scraped by with the help of neighbors and humanitarian aid. It is no longer rare to see groups of old people egging outside supermarkets and pharmacies.

"They are letting us die. No one is able to tell us when all this will be over and how much longer we must live with this hunger," said 76-year-old Tatiana Solovyeva in the town of Makiyivka, just outside Donetsk.

"I don't have any family, I live only on my pension, but now I don't have it anymore.

"I asked for help from my neighbors, some miners. But now they are not getting their salaries either. How can we go on living like this?" she said.