Under the controversial overhaul of the medical cards scheme, about 20,000 people over 70 years of age were legally obliged to hand back their cards by March 2.

In all, 10,181 people have now returned their cards and more cards are on the way, Health Minister Mary Harney revealed last night.

She insisted there would be no extension to the March 2 deadline for returning the cards and warned the HSE would be working with the Department of Social and Family Affairs and the Revenue Commissioners on an "ongoing basis to ensure that the scheme is not abused".

"There was no change to the deadline set out in the Act for persons to hand back their medical cards if their income exceeds the threshold," Ms Harney said last night.

In recent weeks, the Health Service Executive (HSE) has reminded the public that it can share data with state agencies to verify a pensioners' income and warned they face the risk of having to repay the cost of their treatment if they failed to hand back their cards at the beginning of March.

Under the medical cards changes, pensioners on a single income of €700 per week or a couple's income of €1,400 must return their medical card.

On foot of a letter from the HSE in January, pensioners in receipt of a non-means tested medical card were required to make a declaration of their income by March 2. The Government believes it can achieve €20m in savings when all medical cards from over-70s who are now ineligible for them are returned.

Labour's Roisin Shortall last night said there was a lot of confusion about the income thresholds and fear about losing access to a range of services.

"It's putting people in an invidious position expecting them to give up that security. I would hope the department wouldn't be heavy handed in any way," she said. "People are frightened that the department will come after them and penalise them. This has created massive problems for many people who are dependent."

Eamon Timmins of Age Action Ireland last night said some pensioners are angry and are prepared to have the State "come and find them".