Image courtesy of Gensler and OJB

A new filing from Newton-based National Development shows the company’s plans for a life science development on the site of the current WBZ-TV studios have grown even larger.

The company told Boston Planning & Development Agency officials in January that it planned to build a three-building 650,000-square-foot project on the Allston site, which fronts onto Soldiers Field Road, after it completed a new studio building for the station on a neighboring parking lot. City officials gave the OK for the station building late last year.

Now, in to a new letter of intent filed with city officials, National Development Vice President Sherry Clancy said the company is sticking to a multi-phase approach but will ultimately build 700,000 square feet of space over three buildings.

The three class A buildings could rise in two or three separate phases “based on market conditions.” Each would include two levels of parking with “some” ground-floor retail and other uses. The buildings will range from 225,000 to 250,000 square feet of office and lab space, and rise between seven and eight stories, or 135 feet tall.

The plans, Clancy wrote, are expected to conform to the city’s Western Avenue planning study.

Allston and Brighton, along with Watertown, have emerged as the next frontier of life science development in Greater Boston, with Boston-based King Street Properties, Alexandria Real Estate Equities and Harvard Allston Land Co. also planning large-scale biotech projects nearby. Life science developer IQHQ also recently bought an industrial building near Boston Landing, but has not disclosed its plans.