Martin and Kathleen Feldstein's column {op-ed, Sept. 3} saying we shouldn't be concerned about foreign ownership of U.S. assets, which has doubled in the past five years, is typical of the head-in-the-sand lobbying by foreign interests and the Reagan administration against my foreign investment disclosure amendment to the trade bill.

The Feldsteins say "occasional rumblings about restricting foreign investment, such as the idea of requiring official registration" are "to be resisted." They attempt to paint the issue as whether we should impose restrictions, while the real issue is whether we should acquire the information needed for sound policy judgments.

My amendment creates absolutely no restrictions, limitations or preclearance requirements for foreign investments -- which is what virtually every other nation does. Our open door would remain open; my amendment simply asks foreign investors walking through that open door to "sign in."

My three years of extensive research prove that information on foreign ownership now available from the hodgepodge of agencies that collect it is woefully inadequate. My special-interest opponents cite as best the Commerce Department lists (the agency refuses to vouch for their accuracy) and Commerce and Agriculture Department reports (foreign investors are almost encouraged to hide true identities behind dummy corporations). Commerce reports contain only vague aggregate statistics.

A league of foreign interests has teamed with President Reagan -- each with a selfish interest -- to stop the amendment. Reagan uses easy availability of foreign capital to conceal the effects of his spending binge that -- from 1982 to 1985 -- turned the world's top lender into history's largest debtor. Reagan wants to avoid embarrassingly detailed documentation of his irresponsible economic legacy.

Foreigners and administration officials personally pressured senators. One business told a senator it would close down its extensive operations in his state if he actively supported the amendment -- the very kind of economic blackmail proving disclosure is essential. The foreign lobbying pressure has been well funded and intense.

Current ignorance allows foreign interests -- good and bad -- to operate here in virtual secrecy. It shields investments here about which all Americans should be concerned:

The Soviets' attempt in the 1970s to acquire U.S. companies with access to advanced technology was discovered by the CIA only by happenstance;

Reagan's 1986 order freezing Libya's assets here was a meaningless gesture because we cannot find them;

Philippine dictator Ferdinand Marcos siphoned off billions from his country -- and, presumably, our foreign aid -- for Manhattan real estate;

OPEC nations are discreetly buying U.S. oil refining and production facilities and could eventually control vast domestic, as well as foreign, energy supplies and prices.

Foreign investment helped the U.S. emerge industrially. It still brings many benefits. But we are no longer an emerging nation. Decisions vital to our future increasingly made abroad raise troubling questions. Our prosperity, sovereignty and security demand reliable information we don't now have about foreign flags that fly over the U.S. economy.

John Bryant

The writer is a Democratic representative from Texas.