U.S. Warns Beijing on Arms Exports : Weapons: Sanctions may be imposed because of evidence of missile parts being shipped to Pakistan.

The Clinton Administration bluntly warned China on Sunday that it may impose punitive sanctions in the face of mounting evidence that Beijing is exporting missile technology to Pakistan in violation of international guidelines.

The warning was delivered by Secretary of State Warren Christopher during a meeting with Chinese Foreign Minister Qian Qichen. It was the highest-level exchange on the issue between the two countries since the new Administration became seriously concerned about the weapons matter earlier this year.

U.S. officials declined to disclose any details of the conversation, except to say that it dominated the meeting, squeezing out other agenda items such as regional security problems.

A senior U.S. official described the talks as “businesslike” and “positive” but conceded that “both sides realize that we have some serious differences.”

The secretary of state’s remarks were designed to provide added clout to a visit to Beijing today and Tuesday by Lynn E. Davis, undersecretary of state for international security affairs, who is expected to question the Chinese more closely. Beijing repeatedly has denied that it is shipping any missile parts.

The Administration is concerned that the shipments will enable Pakistan to assemble Chinese-designed M-11 missiles, which have a range of about 300 miles and can carry nuclear weapons.

U.S. officials said Christopher invited China to join in President Clinton’s recent call for a worldwide moratorium on nuclear weapons testing and received a “positive response” but no commitment.

Officials also said China agreed to crack down on the shipment of illegal aliens to the United States--both by denying permission for smuggling ships to use Chinese harbors and by publicizing the difficulties that would-be immigrants face.

The controversy over the alleged shipments of M-11 missile parts to Pakistan has become a major bone of contention.

Satellite photos taken over Pakistan last November showed suspicious-looking crates from China, but Washington has no hard evidence that they contained M-11 parts. U.S. law requires that if the President finds that China has violated the guidelines, he must impose sanctions on Beijing.

The George Bush Administration, confronted by similar evidence, postponed the sale of a sophisticated supercomputer to China last December but apparently was not able to persuade the Chinese to halt the shipments of M-11 parts.

Bush had ended an earlier set of sanctions against China last year in return for a pledge by Beijing to honor the guidelines established by the international Missile Technology Control Regime, which bans the transfer of specific missile-making equipment and technology.

Meanwhile, the Clinton Administration has also become worried that China may have increased its transfer of missile-making technology to Iran.

U.S. officials said Davis’ visit to Beijing this week could be crucial in deciding whether the Administration will make a formal finding that Beijing has violated the technology-transfer guidelines--a designation that would require the Administration to impose sanctions.

Under U.S. law, the sanctions must be imposed against China and the business firms that supply it with technology--meaning that some U.S. companies could be penalized in the process. Some members of Congress have said they would try to end China’s “most favored nation” trade status, which was renewed by Clinton in May.