Two senators are asking Treasury Secretary John Snow (search) about Internal Revenue Service resources being used to pay for transportation for department officials.

In a letter to Snow, Sens. Charles Grassley, R-Iowa, and Max Baucus, D-Mont., said they want information on what they regard as "diversion of IRS (search) enforcement dollars and personnel to provide transportation to and from home and work for certain top Treasury officials."

At issue is the use of personnel and resources at the IRS' Criminal Investigation Division (search). The senators want to know among other things the cost of and the rationale for the transportation service.

Treasury spokesman Rob Nichols said the IRS division has been providing transportation and security since August for Samuel Bodman, the department's deputy secretary. That coincided with a warning that U.S. financial institutions could be targets for terrorists.

"While assigning a security detail to the deputy secretary was done in a manner timely with the increased terror threat, we hope it is a temporary situation," Nichols said.

Nichols also noted that the IRS unit provides security for the IRS commissioner.

"We are committed to ensuring that taxpayers' dollars are used wisely and efficiently," Nichols said.

Grassley is chairman and Baucus the highest-ranking Democrat of the Senate Finance Committee, which has oversight of the Treasury Department.

The senators said in the letter that the IRS unit provides up to 10 agents, at an estimated cost of nearly $2 million, to provide transportation service to the department. Nichols said he couldn't comment publicly on those figures but said the department would provide details to the lawmakers.