The architect for the aborted extension of the Fogg Art Museum yesterday called President Bok's decision to abandon plans for the new building "tragic" and asserted that construction was set to start when Bok announced his move.

"It's rather tragic for the Fogg especially" James Stirling said from his home in London. "I was really stunned by the whole thing."

Bok's February I decision, which came the day construction basis for the $10.5 million project expired, ended three years of planning and fundraising and left the future uncertain for the Fogg, which suffers under severely cramped conditions in its current Quincy St. building.

Ready to Start Construction

"We had everything goddamn ready." Stirling said, adding. "Everyone knows we were ready to start at any time."

In recent interviews, several University officials have attributed Bok's decision in part to doubts that Stirling cold complete the project within the original budget.

Stirling's general attitude was the most serious source of worry," said George Putnam '49, the College's treasurer.

In response to these charges, Stirling said. "I've been a professional architect for over 25 years, and... I don't have any comment on that at all."

While plans for the addition were still alive. University administrators never presented Stirling's attitude toward strict budgets to Fogg officials as a major cause for concern. Suzannah J. Fabing, the museum's assistant director, said yesterday.

"I don't understand what Mr. Stirling's at- titude has to do with anything," Fabing added.

Noting that the Fogg had raised virtually all the construction money for the new building. Fabing said that Stirfing frequently made adjustments in his design to keep its cost down "where they did not affect the building's aesthetic."

The Fogg had raised $7.5 million just for the construction, which was estimated to cost $7.8 million. IN a February 2 letter to Fogg supporters, Bok stated that the additional $300,000 was not a factor in his decision.

Meanwhile, Arthur M. Sackler, the medical researcher and art collector who reportedly pledged $7.9 million toward the aborted extension, refused to say yesterday whether he plans to withdraw his gift, calling the question "an internal [Harvard] matter."

Asked what he thought would happen to the money the Fogg has raised for construction. Sackler said, "Harvard people have to address that. The best thing would be to ask Dr. Bok."

He added, "I have always tried to be helpful before to Harvard, and I will try to be helpful in the future."

Bok was unavailable for comment yesterday, s was Fogg Director Seymour Slive, reportedly Sackler's only contact at Harvard.

In a statement he released Thursday, Slive said Bok's decision meant the Fogg would have to return $11 million in pledges and contributions