NEW YORK (Reuters) - The judge in the first trial challenging the government's ban against so-called "partial birth" abortions will allow a pediatrician to testify that a fetus may experience pain during the late-term procedure.

U.S. District Judge Richard Conway Casey, who is presiding over the case set to go to trial on March 29, denied a motion by abortion providers aimed at blocking the doctor's testimony. His decision, which was made public on Monday, rejects arguments that testimony by the government witness is irrelevant and unreliable.

The case in New York is the first of three federal challenges expected to go to trial. Although Casey's rulings are not binding in other jurisdictions, they are being closely watched because they could be cited by government lawyers in the cases pending in California and Nebraska.

Since Congress concluded that a fetus can feel pain during what critics call a "partial-birth" abortion, Casey held that the testimony by Dr. Kanwaljeet Anand is relevant. Anand, an expert on critically ill newborns, is expected to testify that a fetus can experience pain from 20 weeks of gestation.

The judge also ruled the testimony is reliable because of the doctor's extensive experience and research.

Friday's ruling followed Casey's refusal last week to throw out the ban before a trial is held.

The National Abortion Federation had sought a ruling on whether the ban was constitutional before any trial, but Casey said a trial was needed to resolve a dispute over whether the procedure is ever necessary to protect a woman's health.

The NAF, which is the professional association of abortion providers in the United States and Canada, sued U.S. Attorney General John Ashcroft last year to stop enforcement of the law. President Bush signed the measure on Nov. 5, 2003.

The group believes the ban was unconstitutional because it lacks an exception that would permit such abortions if the procedure is necessary to protect a woman's health.