The right to develop offices and retail on a portion of the three-block-long St. John’s Terminal at 550 Washington St. is in contract to be purchased by Toronto-based Oxford Properties for around $700 million, The Post has learned.

The buyers can redevelop 1.3 million square-feet of the future mixed-use complex while the sellers will retain the rights to develop several residential towers. The price equates to $538 per square foot.

Losing bidders, including Vornado Realty Trust, Scott Rechler’s RXR and Brookfield — which was reported by other media to be the winner — were notified this week.

The deal was being marketed for the sellers, Atlas Capital and Westbrook Partners, by a Cushman & Wakefield team lead by Douglas Harmon and Adam Spies.

Oxford is a partner with Related Cos. in Hudson Yards, owns Olympic Tower with the Chera family, and owns 450 Park Ave.

St. John’s Terminal, the 1.1 million square-foot former warehouse that straddles W. Houston St., has been targeted for redevelopment for decades. It is bounded by Washington, Clarkson and Spring streets and the West Side Highway and has an additional 280,000 square feet of air rights.

In December, the City Council approved a plan for the sellers to pay $100 million to the Hudson River Park Trust for another 200,000 square feet of air rights that would be transferred from Pier 40, right across the highway.

As the cash will fix the Pier’s piles and roof, the developers obtained permission to phase in the construction of five buildings with 1,586 apartments — 30 percent of them at lower rents — along with a hotel, offices, and roughly 400,000 square feet of base retail. One building will be targeted for seniors.

St. John’s Terminal was purchased by Atlas and Fortress in Dec. 2012 for $540.8 million from its longtime Eugene Grant family ownership and Fortress sold its share to Westbrook in 2015.

None of the parties could be reached for comment.