The D.C. Zoning Commission, angered by developer Giuseppe Cecchi's demand for more concessions on the massive Techworld high-tech trade mart he plans to build next to the Washington Convention Center, last night rejected most of his requests as unwarranted.

Cecchi told the commission in a recent letter that lenders will not finance the $240 million project unless the panel released him from a requirement that at least part of the building be permanently used as a trade center for the high-technology industry.

But the commission refused the request and turned down several other Cecchi proposals that would have weakened restrictions the agency imposed in March when it approved construction of the combination 910-room hotel and trade center on the vacant two-block site bounded by Seventh, Ninth, I and K streets NW.

Cecchi, the developer of the Watergate complex, sat in the front row of the audience at last night's hearing and muttered sarcastic remarks as the five-member panel ruled against him or modified his requests.

Afterward, he said that he was "not pleased" by the commission's actions, particularly its rejection of the key request on long-term use of the building. But he voiced the hope that the panel will reconsider its decisions when it resumes discussion of Cecchi's requests Aug. 13. The commission took no formal votes on Cecchi's requests last night, but members frequently voiced irritation and anger at his proposals.

"It's gimme, gimme, gimme," commission member John G. Parsons, a Techworld opponent, said of Cecchi's efforts.

Chairwoman Maybelle T. Bennett, who has supported Techworld in the past, said, "I feel betrayed. I want something like this to work. But as far as I'm concerned, we've already given away the company store."

Cecchi told a reporter later that he "didn't ask them to impose such conditions," and he added that if the commission cannot see fit to give him enough of the concessions, including the main one sought by his lenders, he will invoke his matter-of-right zoning, which would permit construction of an office building about 10 percent smaller than the 1.5 million-square-foot plan approved by the commission.

"They're pushing me to [use] matter-of-right [zoning]," he said. "If that's what they make me do, I'll do it. The project is going ahead."

While Cecchi fumed at the commission's actions, Techworld opponents praised the agency for holding fast against further concessions. The commission had already approved Cecchi's plan to build a controversial five-story-high passageway between the two wings of the project, starting 75 feet above Eighth Street, and also his request to narrow the street from its current 100-foot width so that he could turn it into a walkway and courtyard 60 to 85 feet wide.

The Smithsonian Institution, the D.C. Preservation League and the Committee of 100 on the Federal City, an urban planning group, have vehemently opposed the bridge as a "desecration" of Pierre L'Enfant's 1793 plan for development of the nation's capital because it will partially obstruct the street's vista.

"The Techworld team tried to bulldoze the Zoning Commission, and the Zoning Commission stood its ground," said Eric Stern, a lawyer representing the preservation group and the Committee of 100.

Officials of Cecchi's three lenders -- Perpetual American Bank, Equitable Real Estate Investment Management Inc. and Citicorp Real Estate Inc. -- have voiced fears that the high-tech concept might not be economically feasible for the 40-year length of the mortgage. With such concerns, Stern said, "There's no remaining reason to have that bridge" over Eighth Street. Cecchi has repeatedly told the commission that the overpass is necessary to provide large display spaces for high-tech products.

In another matter, the commission, as expected, voted to approve a $90 million hotel, shopping and office complex in Friendship Heights, after slightly trimming the size of the development.

The complex is the first of three large projects planned for a five-acre tract just south of the Maryland line, bounded by Western and Wisconsin avenues, Jenifer and 43rd streets and Military Road. The zoning approval represents an effort by the city government to try to attract the shopping dollars, real estate taxes and jobs that for years have flowed into Montgomery County.