The Hudson River Park Trust is saying that the $600 million Related Companies proposal for Pier 40 in Lower Manhattan is no longer “feasible” due to Related’s demand for a lease of 50 years.

Related, one of the city’s most active developers, had proposed to build on the pier a permanent home for Cirque du Soleil, a space for the TriBeCa Film Festival, and rooftop athletic fields. Currently, Pier 40, situated along the West Side Highway near West Houston Street, contains a parking lot and some playing fields.

The Hudson River Park Trust’s request for proposals for the twostory, 14-acre structure stipulated that the lease would last 30 years, and that an extended lease would require a waiver from the state Legislature.

The chairwoman of the Hudson River Park Trust, Diana Taylor, issued a statement ahead of the board meeting yesterday: “The Related proposal is still not feasible within the prescribed 30-year term and for that reason is not currently being pursued.”

“It is not that their plan doesn’t work, it just doesn’t work if they don’t get a longer lease,” Ms. Taylor said in a telephone interview yesterday. “With a project where you have $120 million invested before it is revenue-producing, it takes a little longer to earn your revenue back.”

Ms. Taylor said she approved of Related’s proposal and said the Hudson River Park Trust tried to come up with a compromise.

“I would have loved to offer a longer lease but that is not within our power. It is up to the state Legislature and we have been told in no uncertain terms that it is not happening,” she said.

By contrast, both the sports complex at Chelsea Piers and another waterfront development plan that has unraveled in recent months, on Pier 57, were able to get waivers from the state Legislature to extend their leases to more than 30 years.

A consortium that organizes day camps and offered up the only counterproposal, the Camp Group, is now the sole contender for the development rights. Ms. Taylor said recent structural problems at the pier are forcing the board to move forward with the Camp Group’s bid despite a feeling that the bid “did not demonstrate the experience, revenue, or fiscal soundness needed for board approval.”

Ms. Taylor said the Trust would give the Camp Group 90 days to work with the nonprofit group Pier 40 Partnership, which has pledged to raise $30 million in private donations, and come back to the board with an updated proposal.

“Camp Group should work with the Pier 40 Partnership on the basis of the concept that they have now informally agreed upon and come back to the Trust in 90 days with a viable proposal that meets all of the criteria outlined above as stated in the original RFP,” she said.

“Trust staff will give them the details of what must be accomplished and the deliverables that are required in order for the board to approve the proposal,” Ms. Taylor said in a statement.

A spokeswoman for Related would not comment on the issue yesterday.