Mismanagement by Voice of America executives will prevent the Reagan administration from achieving its promised $1.3 billion modernization of the broadcasting service by the time the president leaves office, according to an internal review of the project.

The report by the U.S. Information Agency's inspector general found numerous flaws in the project, the first major effort to remodel the agency's broadcast facilities in 25 years. It blamed VOA administrators for underestimating the scope of the project, ignoring new broadcasting technologies and insisting that many aspects of the project first be assessed by numerous consultants.

Morton S. Smith, the VOA's deputy director in charge of the modernization program, acknowledged in an interview that the agency is unable to meet the administration's timetable.

He also said that the delays have increased the price tag for the project to about $1.7 billion. At current funding levels, Smith said it would be fiscal 1994 -- seven years from now -- before the project could be completed.

The VOA broadcasts more than 1,220 hours a week of news, entertainment and information to overseas audiences. Most of the agency's programming originates from its Washington studios at 300 Independence Ave. SW.

VOA officials declined to make public the internal report, completed in mid-1986, saying it is "not ready in final form" and the agency is "considering the possibility that it might find it necessary to conduct additional surveys" of the modernization effort. A copy of the report was made available to The Washington Post by sources who said its criticism remains valid.

It has been no secret that the program, which began with the administration's blessing in 1983, has had serious trouble. Questioned at congressional hearings last spring about delays, officials from the VOA and USIA, the VOA's parent organization, blamed foreign governments, charging that they had been slow to approve agreements for new broadcast facilities.

The internal report, however, cited numerous other problems and said VOA executives had erred by failing to improve existing transmitter sites and refusing to buy "off-the-shelf" equipment. By attempting to design new equipment and dismissing the potential impact of new antenna and satellite broadcast technologies, the VOA may have raised costs, the report suggests.

"VOA's approach to modernization has been too time-consuming and may be unnecessarily delaying the achievement of the proposals," said a July 1986 memo from Anthony J. Gabriel, USIA inspector general. Gabriel said the VOA lacked a documented plan for the project.

"If documentation which provided a clear rationale and justification for major modernization planning decisions indeed exists, it has not been made available," he wrote.

"VOA wasn't ready to run with the ball," said Smith, the deputy director. Although the agency recognized the need for a major improvement of its facilities as long ago as the late 1970s, it lacked an adequate planning staff when Reagan took office, he said.

But Smith rejected the inspector general's criticisms that the VOA was ignoring new technologies as "quite superficial even by the IG's standards." The VOA repeatedly has reviewed technology in planning the modernization, Smith said. When completed, the new system will use the best technologies and be "one that makes sense and works," he said.

Smith repeated the VOA argument that the agency first had to secure agreements for new transmitters to broadcast to the Soviet Union before it could begin planning the new system. Negotiations were protracted and delayed by political conditions in the Philippines and Greece, two prime sites, according to VOA officials.

Smith, a career Foreign Service officer placed in charge of the modernization project in 1984, noted that some VOA stations in Europe are using 1930s-vintage vacuum-tube transmitters that were used by the Nazis.

Because of the delays, Congress is insisting that the VOA spend approximately $150 million in obligated but unspent funds before more funds for modernization can be received.

The slow pace also has prompted questions from others, including members of a USIA advisory commission, about whether the modernization will be completed as envisioned by the president and what it will cost.

Edwin J. Feulner Jr., head of the conservative Heritage Foundation and chairman of the U.S. Advisory Commission on Public Diplomacy, said his panel fears that the delays may have cost the VOA the bipartisan support for modernization it once had in Congress.

"Our concern is losing a marvelous political opportunity," he said, adding that the administration's

budget constraints may pose another challenge to the program.

"If this had been a project in the private sector, I can't believe that it wouldn't have been completed," he said.

Gary Marco, president of National Federation of Federal Employees Local 1418, which represents 160 VOA broadcast technicians, said he agreed with the inspector general's report. The modernization, he said, is "extremely expensive and not very well thought out."

"Why should a large organization with a large corps of engineers have to contract out all the work?" he asked.

Smith described the union's complaints as "garbage" and said its chief interest is "featherbedding." At many commercial stations, announcers now handle chores that VOA broadcast technicians perform, he said.

Marco praised Charles Z. Wick, USIA director, for winning White House support for the VOA's major overhaul. "In my opinion, Mr. Wick did his job, but it just hasn't moved down the line," Marco said.