WASHINGTON – Sponsors of Medicare discount drug cards complained Friday that a government Web site lists some prices wrong. But the top Medicare official defended the accuracy of the site’s price comparisons.

“We stand by those prices,” said Mark McClellan, administrator of the federal Centers for Medicare and Medicaid Services.

The Medicare Web site is posting the best guaranteed price from drug card sponsors, McClellan said in a telephone interview with The Associated Press. The Web site is managed by DestinationRx, a small, California-based company that Medicare hired without seeking bids.

A day after the Bush administration rolled out the online price comparison as part of the new discount drug card program, several sponsors said it is showing prices different from what they submitted.

“Some are too high. Some are too low,” said Craig Fuller, president of the National Association of Chain Drug Stores, a partner in the Pharmacy Care Alliance drug card.

“The site is ultimately going to be very valuable, but there are serious technical problems that need to be addressed,” Fuller said.

Medicare is showing prices for prescription drugs that are off by 15 percent to 20 percent, Fuller said.

Officials for three other card sponsors – Medco Health Solutions Inc., United Health Group’s AARP card and Walgreens – also reported problems. However, Walgreens spokeswoman Laurie Meyer said technicians determined that the company, not Medicare, was to blame for inaccuracies that led to posted prices for generic drugs that were “noticeably higher” than Walgreens intends to offer.

The card sponsors said they are concerned that people can begin signing up for cards on Monday based on erroneous information that, in most instances, would put their cards at a disadvantage.

McClellan said Medicare beneficiaries could wait several weeks and still enroll in time to have their cards when they become active on June 1. Medicare is continuing to evaluate applications from card sponsors and still could add cards.

Medicare began posting drug prices on its Web site Thursday, allowing people to compare the new Medicare-approved discount drug cards and decide which offer the best prices.

On the Net: Centers for Medicare and Medicaid Services: http:///www.medicare.gov/AssistancePrograms/

About half of the 40 national and 32 regional cards were included in the initial listing of prescription drug prices. Medicare said it would update the site every Monday. The same information can be obtained by calling Medicare at (800) 633-4227.

A dozen Democratic senators asked Medicare to allow people 30 days to change cards because so much information is not yet available. Once enrolled, Medicare beneficiaries can change cards only at the end of the year.

McClellan said he does not think a grace period is necessary.

The administration is predicting that the cards will offer significant savings, but critics said seniors could get similar prices, without discounts, through online pharmacies and do even better using Canadian pharmacies.

On the Net: Centers for Medicare and Medicaid Services: http:///www.medicare.gov/AssistancePrograms/