President Ferdinand Marcos of the Phillippines yesterday suspended construction of a controversial nuclear power plant that has become a test case for U.S. nuclear export policies.

In a surprise announcement, Marcos named a special commission, including a major opposition party leader, to probe the safety of the $1.1 billion project that has been going up on the Bataan peninsula 65 miles west of Manila.

"Unless they remove my doubts about the safety of operation," Marcos said, "I am going to seek the cancellation of the contract with Westinghouse on grounds that there is a violation of an implied warranty of safety for our people."

The Westinghouse Corp. application for permits to export a 626-megawatt reactor with its radioactive fuel, steam generator and other equipment has been pending before the State Department and the Nuclear Regulatory Commission since 1976.

Opponents charged that the Plant site is too near an active earthquake zone and that it sits on the slope of an inactive volcano, Mt. Natib, which some reports hold may only be dormant. They also alleged that the Westinghouse design is faulty in its fire proetection arrangements and in its turbine structure.

However, foreign environmental worries have traditionally been ignored in U.S. consideration of export permits. To do otherwise, authorities have argued, would infringe on the rights of the countries involved to make their own environmental decisions.

President Carter issued an executive order this spring ordering environmental review of major federal actions overseas, and the Phiippines case has become the first major test of the scope of that order. Regulations implementing the order are to be issued in September, and little action is expected on the Westinghouse applications for export licenses before then.

While awaiting a ruling on national security impact of the application from the State Department, Westinghouse has asked the Nuclear Regulatory Commission to allow export of $5 million worth of nonsensitive equipment, including sewage treatment units and air compressors. The NRC staff has recommended aporoval but the full commission has not acted.

Meanwhile, opponents of the project have tried to tie it to alleged human rights abuses by the Marcos government, to large commissions paid friends of Marcos by Westinghouse and to presence of 8,000 Americans at the giant Subic Bay naval base 16 miles from the reactor site.

"We feel really good" about Marcos' ruling, said Nicky Perlas, Washington head of the Campaign for a Nuclear Free Philippines. "But we're keeping our fingers crossed. It may be only a ploy by Marcos."

Westinghouse spokesman Paul Jones said the company is "confident that a thorough and objective investigation of the safety of the plant will prove it can be operated without undue risks to the health and safety of the Philippine public."

Westinghouse said earlier that the Philippines already is suffering brownouts from power shortages and that the delay even before Marcos' decision had pushed the plant's completion date from 1981 to 1983.

"A lot of countries are watching the United States on his one," said Dwight Porter of the firm's Pittsburgh headquarters. "Suddenly the issues of nuclear export are not non-proliferation (of atomic weapons) but something else."