WASHINGTON — The Internal Revenue Service, noting an escalation in identity theft scams, is raising alarms about e-mails designed to dupe taxpayers into revealing personal financial information.

IRS and Treasury Department officials have noticed an increase this winter in the frequency and sophistication of "phishing" schemes that use the tax agency's logo to lure victims.

"There does seem to be a proliferation of them this filing season," Richard Morgante, commissioner of the IRS wage and investment division, said yesterday.

The Treasury inspector general for tax administration, which investigates anyone impersonating the IRS, found 12 separate Web sites hosting such "phishing" schemes operating in 11 different countries, from the United States to Aruba to South Korea.

The inspector general has gotten more than 400 complaints to date this year. The IRS has been made aware of about 1,500 cases since November.

In a "phishing" scam, identity thieves send e-mail masquerading as official communication from a government agency, bank or other institution in an attempt to solicit personal data such as account numbers, passwords or credit-card numbers.

The thieves use the information to steal a person's identity and commit financial crimes, such as using the victim's credit cards or applying for new ones, applying for loans or filing fraudulent tax returns.

"Phishing" e-mails purporting to come from the IRS often tell taxpayers they're due a refund and direct them to a false IRS Web site. The e-mail address may include "irs.gov," such as tax-refundsirs.gov or adminirs.gov.

The communication and Web sites might look like real, but they're not, Morgante said. The IRS does not communicate with taxpayers via e-mail. Nor does it ask people for passwords, personal identification numbers or other secret information. Those who receive fraudulent IRS e-mail can contact the inspector general at (800) 366-4484.