The Japan branch of a UNESCO advisory panel has again asked the Tokyo Metropolitan government and developers to respond to its heritage alert to stop a redevelopment project for the Meiji Jingu Gaien, a historic and lush park in the center of the capital.

The International Council on Monuments and Sites, or ICOMOS, issued the alert in September this year to Tokyo and businesses linked to the project. The project led by Mitsui Fudosan calls for the felling of 743 trees, all more than three meters tall.

It said "Jingu Gaien... represents an outstanding cultural heritage, unparalleled in the history of urban parks worldwide."

ICOMOS Japan held a news conference at the Tokyo Metropolitan Government Buildings on Tuesday.

It asked for a response, saying the original deadline of October 10 had been missed.

ICOMOS says it is unusual for it to make a second request after issuing a heritage alert. The panel is asking Tokyo to redo its environmental assessment that led to the endorsement of the project.

ICOMOS Japan Director Ishikawa Mikiko described the lack of a formal response as extremely regrettable and a serious situation.

She suggested it is better for everyone to think about how to pass the huge green space to future generations.

The heritage alert is not legally binding. One operator of the project has complained it was issued unilaterally at ICOMOS's own discretion. Tokyo has countered that redevelopment procedures are being conducted properly in accordance with relevant laws.