New York police remained on high alert Saturday as authorities continued debating whether a reported subway terror plot was a legitimate threat or an overblown hoax.

Federal officials maintained their skepticism, but issued a conciliatory statement, saying they respect Mayor Michael Bloomberg's decision to beef up security in the subways.

Homeland Security Secretary Michael Chertoff said Saturday that Bloomberg was right to err on the side of caution.

"The secretary respects the mayor's judgment and believes that the security precautions being taken by Mayor Bloomberg and other New York officials are absolutely an appropriate response," Chertoff said in a statement.

On Thursday, Mayor Bloomberg and police Commissioner Ray Kelly went public with the news that terrorists planned to use timed or remote-controlled explosives hidden in briefcases and suitcases, and under strollers.

Mayor Bloomberg said it is better safe than sorry.

"If I've got to make a mistake it's got to be on the side of protecting the people of this city," the mayor said Friday morning. "In this case I don't think that we made a mistake. I think that we took the appropriate action, and hopefully we will prevent anything from happening."

So far three suspects have been arrested in Iraq in connection with the alleged plot. Sources say authorities are investigating whether a fourth man traveled to New York as part of the scheme.

Thousands of extra police officers were sent to the city's transit system and the number of bag checks was doubled.

A Department of Homeland Security memo warned that terrorists may have traveled to New York to put remote-controlled bombs in briefcases and baby carriages in an attack scheduled for or around Sunday. It cautioned, however, that FBI and Homeland Security doubted the threat's credibility.

Hours before saying they respected Bloomberg's judgment, Homeland Security officials were still playing down the threat.

"Although the threat information was very specific, it still remains of doubtful credibility," department spokesman Russ Knocke said.

New Yorkers responded to the government's warning with a mix of skepticism and resignation, saying a cycle of threat, police response and no attack had become just another element of life in the city since the Sept. 11 terror attack on the World Trade Center in 2001.

Meanwhile, New York Civil Liberties Union has suspended its bid to stop random bag searches by police. It was seeking an injunction against the city police department's search policy. But now the group is asking for a two-month delay so its lawyers can examine how the latest terror alert affects the search rules.

Source: Xinhua