UPDATE 2-NY MTA, Hudson Yards developer at an impasse

(Adds comment from Tishman in 7th graf)

By Joan Gralla

NEW YORK, May 8 (Reuters) - Talks between New York's Metropolitan Transportation Authority and Hudson Yards developer Tishman Speyer hit an impasse because the firm tried to delay the deal until all of the site was re-zoned, an agency spokesman said on Thursday.

"This demand changed the economics of the proposed deals and the certainty of payments to the Metropolitan Transportation Authority," spokesman Jeremy Soffin said in a statement.

Economists have predicted that several of the $51 billion dollars of public and private projects planned for the city over the next few years will be delayed, reduced or abandoned.

The subprime mortgage crisis has sliced Wall Street's profits, imperiling the city's tax collections and curbing banks' willingness to lend to developers.

Earlier, the biggest U.S. mass transit agency, whose midtown rail yards is one of the last under-developed tracts of prime Manhattan real estate, said it "stopped the clock" at 4:59 p.m. on Wednesday after negotiators missed the seven-day deadline.

Tishman Speyer had preliminarily agreed to pay the authority $1 billion for the 26-acre Hudson Yards site, where it planned to build giant office and apartment towers after first erecting a platform over the yards.

"This is a highly complicated deal and we have been negotiating in good faith with the MTA for several weeks. We share the same goal as the MTA and (New York City) to transform Hudson Yards into a successful and vibrant community," said Robert Lawson, spokesman for Tishman Speyer.