UPDATE 2-U.S. House backs anti-abortion amendment

* House backs ban on federal funds for abortions

* Measure helps win support from moderate Democrats

(Updates with comments)

By Donna Smith

WASHINGTON, Nov 7 (Reuters) - The U.S. House of Representatives voted on Saturday to tighten a ban against using federal funds to finance abortions under the proposed Democratic healthcare reform legislation.

Opposition Republicans joined forces with anti-abortion Democrats to pass the amendment to the healthcare legislation on a vote of 240-194.

The House approved a sweeping healthcare overhaul on Saturday on a narrow 220-215 vote. The battle over President Barack Obama's top domestic priority now moves to the Senate.

The anti-abortion amendment angered liberal Democrats who support abortion rights, but its passage helped win backing for the legislation from moderate Democrats, many of whom had refused to support the bill without strengthening language that bars using federal subsidies to fund abortions.

"Placing onerous new restrictions on a woman's right to choose sets a terrible precedent and marks a significant step backwards," Democratic Representatives Louise Slaughter and Diana DeGette, co-chairs of the congressional pro-choice caucus, said in a statement.

The amendment offered by Representative Bart Stupak, a Democrat, bans the proposed new government health insurance plan from covering abortions except in cases of rape, incest or where the life of a mother is threatened.

Policies purchased with federal subsidies from private insurers will have the same restrictions and women seeking abortion coverage will have to purchase separate insurance riders with their own money.

DeGette, during the House debate, called the idea of purchasing separate abortion riders "offensive to women," arguing that no one plans for an unwanted pregnancy.

Stupak made the case that the amendment applies current federal law to the proposed healthcare legislation.

The House-passed healthcare bill will eventually have to be resolved with any overhaul legislation passed by the Senate.

House Republican Leader John Boehner said there were no guarantees the strict ban on using federal subsidies to finance health policies with abortion coverage would survive the negotiations on a final bill.

"Just because we pass an amendment to help facilitate the passage of what I think is a bad bill, does not mean that the language that this House votes on is committed to by the Democrat leader in this House," Boehner said.