The state selection committee for the developer of the commercial sector of the subway yards on Boylston St. may disqualify one of the three development teams under consideration because the architectural firm and the developer have separated.

Boston Urban Associates (BUA) and The Architects Collaborative (TAC) both sent letters to the committee last week stating they would not be able to work together on the project, David Carter of the State Planning Office, said yesterday.

Carter said he expects the committee to make a final decision on whether it will consider new proposals from BUA or TAC when it meets this Tuesday.

The committee has known about the development team's problems for over a month. The committee informed the firms in a letter dated October 5 that it would consider only one of the two firms for the final contract.

Thomas Steele '62, president of Perini Land and Development Company, said yesterday his company has "a verbal understanding" with TAC to serve as its developer if the committee continues to consider TAC.

Zuckerman said yesterday he hopes he will be able to form a development team with Hoskins' new firm, Hoskins, Scott, Taylor and Company, as his architect.

The other firms the committee is considering are Ben Thompson and Associates and the Cambridge Carbarn.

Mortimer S. Zuckerman, Urban Associates president, said yesterday the split started last May when Joseph Hoskins, the architect working on the project, left TAC two days before Zuckerman submitted his development plan to the committee. "We didn't create the problem--they had the problem," Zuckerman said.

Zuckerman said TAC then reneged on a verbal agreement that would have allowed him to review the firm's plans well in advance of their submission to the committee. The architectural firm wanted to change its position in the development team from a partner in a joint venture to an architect providing a service, he added.

He said he felt uncomfortable working with TAC because Hoskins was the only member of the collaborative he knew. "It's a personal business," he said.

John C. Harkness, TAC president, said yesterday the firm sent its standard contract to BUA. But BUA wanted such unacceptable changes as the right "to fire us without cause," he said.