State officials could yank money for an amateur sports complex in Coney Island if Mayor Giuliani insists on first building a minor league ballpark for the New York Mets, Brooklyn legislators warned at a public hearing.

Meanwhile, documents prepared for the review underway in Community Board 13 put the ballpark's projected cost at $24 million, $4 million more than approved by the city's Economic Development Corp.

A similar ballpark planned for a Yankee farm team at the Staten Island ferry terminal saw its projected cost double to $40 million.

Brooklyn documents also cite $7 million more for "off-site improvements," bringing to $31 million the cost of a new home for a Mets' affiliate in the Class A New York-Penn League.

Assemblyman Clarence Norman (D-Crown Heights) spoke for 12 state legislators in urging the EDC to move ahead on both the ballpark and Sportsplex at the same time.

"We have no objection to the proposed ballpark, except that it could jeopardize development of the Sportsplex, a much more worthy project," Norman said. He spoke Monday at the first of three nights of hearings at Coney Island Hospital that conclude tonight.

Norman said Brooklyn lawmakers worked hard to persuade Gov. Pataki and legislative leaders to commit $30 million to the Sportsplex, an amount matched by Giuliani in the city budget. Norman said the mayor's stalling will "erode" continued state support.

Sportsplex backers want the arena and ancillary facilities to go on the same Steeplechase site as the ballpark. The mayor, who says the Sportsplex must wait until the ballpark is built, is eying a site just to the west.

EDC officials heard from legislative, business and community leaders urging support for the Sportsplex.

"We're still in discussion about the Sportsplex, trying to get some clarification on the Ogden report," said EDC spokesman Bruce Brodoff, referring to a report prepared by the Brooklyn Sports Foundation, prime Sportsplex backers, showing the facility could turn an operating profit with a limited number of commercial events.

"The bottom line is there is room for both, and money for both," Community Board 13 Chairman Martin Levine said.