PORTLAND — The Friends of Congress Square Park, the neighborhood group leading opposition to a planned hotel event center in public space at Congress and High streets, has launched an attempt to change a law protecting the city’s parks.

The Friends are mounting a citizens’ initiative to change the city’s Land Bank Commission ordinance, which establishes protections for designated open spaces that have environmental or recreational values.

The group hasn’t released details about changes it proposes for the law, but Frank Turek, the Friends president, listed several problems with it in an Aug. 28 press release.

“The focus of the ordinance is entirely upon natural undeveloped properties, and cherished downtown open spaces such as Monument Square and Congress Square would not be eligible for Land Bank designation,” Turek said.

The fact that the ordinance allows the council to approve the sale of open space by a majority of five votes provides little protection, he added.

The council is expected to take up the issue of selling about two-thirds of Congress Square Plaza at a meeting on Monday, Sept. 9. On Aug. 21, the council’s Housing and Community Development Committee recommended a proposed agreement to sell about 9,500 square feet of the public space to RockBridge Capital LLC for nearly $524,000.

RockBridge and co-developer New Castle Hotels & Resorts are finishing a $50 million renovation of the former Eastland Park Hotel, and plan to reopen it in December as the Westin Portland Harborview. The developers have hoped to acquire a portion of the plaza to build an adjoining center for meetings and events.

It’s not clear if or how changes in the Land Bank ordinance might affect the sale, or if the plaza would be protected by a revised law.

The Friends will have to collect 1,500 signatures from registered votes to put the changes to a referendum.

William Hall can be reached at 781-3661 ext. 106 or whall@theforecaster.net. Follow him on Twitter: @hallwilliam4.