Following reports of health insurer Wellpoint's (WLP. N) hiking some premiums by 39 per cent, U. S. lawmakers called upon the chief executive of the unit to confirm the reports on Tuesday.

A letter was sent to Angela Braly by House Energy and Commerce Committee Chairman Henry Waxman and Representative Bart Stupak, both Democrats. The letter requested Braly’s testimony at a hearing on February 24 after reports of premium hikes by Anthem Blue Cross of California, a Wellpoint unit.

It was reported last week that the rate hike would be seen by about 800,000 Anthem Blue Cross of California customers with individual health insurance plans by 39 per cent on March 1.

In the letter it was said that the report was being investigated by panel's oversight and investigations subcommittee for which information and internal documents were sought.

A list of proposed premium hikes from January 2009 through December 2010 was also asked by the lawmakers.

Details regarding the hike reports were also asked by Health and Human Services Secretary Kathleen Sebelius.

Wellpoint spokeswoman Kristin Binns said on Tuesday that, “The company was reviewing the congressmen's letter.”

Anthem spokeswoman Peggy Hinz on Monday said, “The company had not made public any specific rates.”