NEWARK, N.J. — Amazon’s plans to put a cargo hub at Newark Liberty International Airport have been grounded. The Port Authority of New York and New Jersey, the airport’s operator, said in a statement Thursday that negotiations over the past year have failed to produce an agreement.

Last August, the Port Authority’s board approved negotiations on a 20-year lease for two 1990s-era buildings at the airport that Amazon was to redevelop into a state-of-the-art, 250,000-square-foot air cargo campus.

Some labor groups and local officials had opposed the plans, claiming the hub would have increased traffic in an already congested area. They had also had criticized Amazon’s working conditions.