WASHINGTON (Reuters) - A bipartisan group of U.S. senators re-introduced a bill on Tuesday aimed at helping generic drug companies bring out a cheaper version of pharmaceuticals.

Makers of branded drugs have long been accused of refusing to provide samples of drugs on a government list of restricted medicines. Without the samples, generic competitors cannot prove their medicines are as safe and effective as the more expensive versions.

To combat this, Republican Senators Chuck Grassley and Mike Lee and Democrat Amy Klobuchar and some two dozen other senators from both sides of the aisle introduced a bill that spells out a legal pathway for generic companies to press for the samples.

In the U.S. House of Representatives, Rep. David Cicilline, a Democrat, and Jim Sensenbrenner, a Republican, and others introduced an identical measure.

The bill is one of several aimed at bringing down, or at least containing, the high and rising price of many medicines. It was considered in the previous Congress but failed to become law.