The union that represents thousands of Internal Revenue Service workers has attacked a proposal that would scale back taxpayer assistance centers, where people can get free help on their taxes.

Nationally, the plan would eliminate 700 jobs at those walk-in centers and at telecommunication hubs in Boston, Chicago and Houston.

There was no word on whether any of the Maine offices would be affected. The IRS currently staffs a walk-in center at 217 Main St. in Lewiston and in four other Maine cities: South Portland, Augusta, Bangor and Presque Isle.

“I cannot conceive of a worse idea by this agency,” said Colleen Kelley, president of the National Treasury Employees Union.

She called the proposal “an attack on those who provide assistance to taxpayers.”