Pharmaceutical giant Pfizer raised the U.S. price of nearly 100 drugs by about 20 percent so far this year, according to a new report.

The price hike comes as Pfizer and the rest of the pharmaceutical industry get heat from Congress over high drug prices.

The Financial Times reported Friday that the drug maker raised the prices of 91 drugs on June 1 from 5 to 13 percent. The U.S. drugmaker also raised prices in January, bringing the full average of the increases up to 20 percent per drug.

Pfizer responded that it has "very comprehensive and extensive access programs for those that cannot afford or do not have good insurance."

It pegged the average net selling price increase at 4 percent in the U.S.

The increases come as the pharmaceutical lobby tries to rehab its image after highly publicized price increases for brand-name and generic drugs.

The industry's main lobbying group, the Pharmaceutical Manufacturers and Research of America, put in new membership criteria earlier this month that would boot companies that don't spend enough of their profits on research and development.

A common defense from drug companies is that they price drugs so high to recoup high research and development costs. But consumer and patient advocates have complained that there is little transparency surrounding those costs, making it difficult to determine how much of the revenue goes to research or to marketing.

Congress has scrutinized the drug industry in recent years over the high costs. However, no reforms to address prices are on the horizon, except for potential changes to the Food and Drug Administration drug approval process.