Donald Trump is being sued for $1.3 million by three real estate brokers who say he has failed to pay them in full after the profitable sale of land and apartments he owned on the former West Side Manhattan rail yards.

The lawsuit centers on the billionaire developer's sale of 77 acres of riverfront and three buildings to the Extell Development Corp. and Carlyle Group for $1.8 billion. Parties to the October deal said it was the biggest residential sale in the city's history.

Barbara Corcoran, founder and principal of one of New York's major real estate firms, and two of her brokers say in the lawsuit that they have a contract that set the terms of their compensation from the sale.

The contract, their court papers say, called for Trump to pay them $4 million in commissions — a $2 million base commission for arranging the financing to develop the properties and a $2 million percentage commission after the properties' sale.

The brokers' lawyer, Richard C. Seltzer, said Trump paid his clients — Corcoran, Carrie Chiang and Susan Cara-Madden — $2.7 million, leaving $1.3 million due.

Trump replied Wednesday that he does not owe the brokers any money — yet.

"The agreement is very clear," Trump said. "I only pay them when I get paid. We haven't gotten the money yet. For her to bring a lawsuit against me is insane."

Trump complained that Corcoran was ungrateful since he had given her "tens of millions of dollars in business over the years" and had done favors for her. He said he was through doing business with her.

Trump lawyer Jason Greenblatt said there is no date when the payment to the brokers comes due.

"When we get paid our distribution, they will get paid their share," he said. "They're asking for something they're not owed at this time."

Seltzer, the brokers' lawyer, said Trump can say he doesn't have the money because he immediately reinvested it in real estate so he could avoid paying capital gains taxes. He said the sale of the property "triggered his obligation to pay the balance of the $4 million."

The 77-acre parcel stretches from 59th Street to 72nd Street on Manhattan's Upper West Side, along the Hudson River.