Free newspapers distributed to subway commuters are a major cause of subway track flooding, a Metropolitan Transportation Authority investigative task force has found.

Leftover stacks of papers such as AM New York and Metro that blew onto the tracks and clogged drains were partially responsible for the crippling subway flood of September 8, 2004, which affected 15 subway lines, according to the task force’s findings.

An MTA board member who headed the task force, Barry Feinstein, yesterday outlined the results of a months-long investigation into causes of that flood for the MTA board, but did not release the report to the public.

“Hand-distributed free newspapers have been and will continue to be a major cause of clogging the drains,” Mr. Feinstein said. He also identified overloaded sewers and catch basins clogged with debris as contributors to track floods.

Transit pumps drain 13 million gallons of water out of the subways and into city sewers on an average sunny day, according to Mr. Feinstein. Clogged sewers make it impossible for the pumps to keep up on rainy days.

Mr. Feinstein said track flooding has escalated since newspapers such as AM New York and Metro were launched about three years ago. His biggest complaint concerned the stacks of extra newspapers left behind after the morning rush, which add fuel to track fires and contribute to flooding, he said.

“We have complained bitterly for a long time about the free newspapers. We must stop the distribution of free newspapers on our property, or require these papers to be kept in bins where they cannot end up on the subway tracks,” Mr. Feinstein said.

AM New York has a daily circulation of 325,000 and Metro has a daily circulation of 300,000.

Mr. Feinstein said the report refutes a charge by the MTA’s inspector general, Matthew Sansverie, that the flood was a result of “historic neglect” of track maintenance.

“We have no comment because we haven’t seen the report,” a spokesman for Mr. Sansverie’s office, Jim Bono, said. “When we asked for a copy of the report, we were denied.” Mr. Bono added that the inspector general’s report also underscored the newspaper problem.

The senior attorney for the Straphangers Campaign, Gene Russianoff, issued a statement in which he criticized the MTA’s decision not to release the task force’s report. “It should have been possible to issue a written response that deleted information that would undermine subway security,” he said. “Talk about a lack of transparency.”

A spokeswoman for Metro, Lori Rosen, said the newspaper is “doing everything we can to rectify the problem. We put in a recycling program that encourages commuters to redistribute their papers.”

Metro’s goal is to recycle 40,000 papers a month, she said.

“Our newspapers are not distributed on MTA property,” a spokesman for AM New York, Floyd Weintraub, said in response to Mr. Feinstein’s charges. He noted that Metro and AM New York are distributed only outside of subway stations, and it is purchased newspapers that are sold on train platforms at kiosks.

Mr. Feinstein acknowledged that purchased newspapers were also found on the tracks, but not at the same volume as free papers. “People are paying for those newspapers and they take them with them to work. They’re not leaving them on the subway, they’re not tossing them on the tracks,” he said.

Mr. Feinstein’s recommendations to the board included setting up bins for free newspaper distribution and collection. He also requested that the MTA and the city “work together to get sewers and catch basins fixed and to properly repair streets,” and admitted that while subway flooding can be alleviated, it can never be prevented altogether.