WASHINGTON, July 30 — The Federal Bureau of Investigation and the Internal Revenue Service raided the Alaska home of Senator Ted Stevens on Monday in search of evidence about his relationship to a businessman who oversaw a remodeling project that almost doubled the size of the senator's house, federal law enforcement officials said.

The decision to raid the home suggests that the corruption investigation focused on Mr. Stevens, a long-serving Republican and former chairman, has taken on new urgency.

The businessman, Bill J. Allen, the founder of an oil fields service company that has won tens of millions of dollars in federal contracts with the senator's help, has pleaded guilty to bribing state legislators.

The F.B.I. confirmed that the raid on Mr. Stevens's home in the Alaskan ski resort city of Girdwood, about 40 miles south of Anchorage, began about 2:30 p.m. Alaska time, or about 6:30 p.m. Eastern time.

In Washington, Mr. Stevens issued a brief statement: "My attorneys were advised this morning that federal agents wished to search my home in Girdwood in connection with an ongoing investigation. I continue to believe this investigation should proceed to its conclusion without any appearance that I have attempted to influence the outcome."

A spokesman for the Anchorage office of the F.B.I., David Heller, would not discuss details of what was being sought in the raid and referred calls to the Justice Department's public integrity division in Washington. The division handles major corruption cases involving public officials.

Mr. Stevens is one of more than a dozen current and former members of Congress who are known to be under scrutiny by the F.B.I.

His case may be the most politically consequential. He is the only senator known to be under criminal investigation, and he continues to wield power on the Appropriations Committee, which controls how the federal budget is distributed. Mr. Stevens, 83, is up for re-election next year and has suggested that he will seek another term.

Mr. Stevens has been caught up in a larger corruption investigation in Alaska that resulted in raids last year on the homes of six state lawmakers, including the senator's son, Ben, who was then president of State Senate. All of the state lawmakers are under scrutiny over their relationships with Mr. Allen and his company, VECO, and other large Alaska companies.