With forecasters saying the region is overdue for a major hurricane, Mayor Bloomberg is opposing a city agency’s idea of allowing New Yorkers to carry pets on subway evacuation routes.

“In an emergency we have to evacuate human beings, and that is where our priority has to be even if some people don’t ever want to hear it,” Mr. Bloomberg told reporters.

This marks the second time in five weeks that Mr. Bloomberg rapidly repudiated his subordinates’ efforts after word leaked to the press about their plans.

Mr. Bloomberg acknowledged the awkward overruling by saying, “I was informed this morning that that was an idea that had come from our Office of Emergency Management, so I won’t be too critical.”

Mr. Bloomberg declared there would be no pets – with the exception of small dogs and cats – on subways and buses if city residents need to make an emergency evacuation. Mr. Bloomberg drew laughter from the usually subdued City

Hall press corps when he ticked off the pets that would not be permitted on buses or subways: horses, donkeys, alligators, boa constrictors, and tigers.

Pet owners’ hopes were raised after a news report yesterday said OEM had asked the Transit Authority about easing its strict pet policy for trains and buses in the event of a hurricane or other disaster so that people wouldn’t resist evacuation.

A spokesman for the agency, Jarrod Bernstein, dismissed the notion that the mayor was shooting down one of OEM’s ideas. He said the agency was simply gathering information to preempt the New Orleans-style problem of people refusing to leave because their pets had no safe haven.

A political consultant, Hank Sheinkopf, said that while city commissioners act independently for the most part, the mayor has the final say.

“Ultimately in any administration the mayor is the boss,” Mr. Sheinkopf said. “You can say or do whatever you want, but the mayor will tell you what he wants. And his management style is certainly to have one voice and no chaos.”

In a more serious case, Mr. Bloomberg last month caused a stir by overruling his top welfare aides on their plans to ease restrictions on eligibility for food stamps.

Hurricane planning is taking on new urgency as the city rushes to complete a formal evacuation plan by the end of next month. City officials today will unveil an American Red Cross mobile command center in Queens, part of a fleet of 16 units for which the City Council paid $1 million last year.

Meteorologists say New York City and the region are long overdue for a severe storm. Parts of Long Island that jut out are particularly at risk, as are low-lying areas. Manhattan’s tall buildings also present a hazard because wind levels increase at higher elevations.