Japanese banks, after a period of government-imposed cautiousness, have reentered world financial markets, underscoring Tokyo's growing role as an emerging international center of finance.

Customers ranging from Indonesia to Mexico are lining up for syndicated loans arranged by Japanese bankers. The market for what sometimes are called "samurai bonds" is booming again, with a year's backlog of foreign applicants waiting in a queue. For Japan's highly valued yen loans, there are more seekers than the markets can handle.

Tokyo's commercial and investment bankers only partially are freed from government restraints imposed in the late 1970s, but they see coming another boom period that will enlarge the Japanese role as a major force in international capital markets.

At the Bank of Tokyo, one of the world's leading participants in syndicated loans, Mamoru Hasimoto ticked off the latest deals -- loans to the governments of Malaysia and Tailand, to a state-owned steel holding company in Brazili, to a national bank in Mexico.

"So we are everywhere now," concluded Hashimoto, deputy general manager of the bank's international investment division.

The story is much the same at Daiwa Securities Co., Ltd., an investment banking house that has placed several new issues of the coveted "samurai bonds." Daiwa and three other houses have a list of 30 customers waiting to float the yen-dominated bonds in Japan where interest rates are only about half those in western countries.

Japan's appeal in the world borrowing market is so great and its bankers' zeal so expansive that foreign observers believe that the 1980s may see this country's financial growth match the pace of Japan's export surge of the 1970s.

"Japan is a major player now," said Eric W. Hayaden, an economist and vice president of the Bank of America's Asia division. "By the end of this year, Japanese banks will have booked nearly $50 billion in syndicated loans. It has really taken off. And the interesting thing is that so much of this has happened only in recent years.

"I think that Japanese banks are as interested in dominating international financial markets as Japanese steel companies or Japanese automobile companies are in dominating their industries around the world."

It is a new twist. Until the early 1970s, partly because of their own timidity and partly because of government restraints on exported capital, Japan's banks were a minor factor in international markets. They made their money lending to growing domestic industries and went abroad, when at all, merely to service Japanese companies engaged in export business.

The '70s were a stop-and-go period marked by sudden surges overseas and sudden retreats. Banks and the ministry of finance got scared after the first great oil shock in 1974. Foreign lending subsided but took off again in the late 1970s -- in 1978 and 1979 Japanese banks accounted for more than 20 percent of the world's syndicated lending. Then the ministry of finance clamped on the controls again.

The finance ministry gradually has eased its restrictions but has made it clear verbally to bankers that it will maintain a measure of guidance. The bankers hope for slower but more sustained growth in lending that will erase Japan's financial image as an erratic splurger. They have a target for syndicated loans that would amount to between 10 and 15 percent of the world market this year. Investment houses envision approving only two or three samurai bond issues a month, which would mean working off the customers' backlog in about a year.

The zest with which bankers are moving overseas, however, suggests these limits will be reached quickly. Commercial banks are now much more enthusiastic about shaping the international syndications rather than merely participating in them. Only a few years ago, it was rare to find a Japanese bank acting as the lead manager in a syndication. "We usually just sat in our offices and waited for the telexes to come in from other banks," said the Bank of Tokyo's Hashimoto.

The reasons for their easy expansion are not hard to find. Japanese banks now operate all over the world, and with the trend to industrial expansion at home slowing down, have an incentive to direct their efforts elsewhere. They have developed a new sophistication in locating money in Europe, Hong Kong and Singapore for syndicated loans to choice customers, almost always foreign governments or international institutions like Asia Development Bank.

The samurai bonds and yen loans are floated inside Japan where interest rates are lower than anywhere except in Switzerland. Daiwa securities recently managed a bond issue for the French national railway system carrying an interest rate of only 8.2 percent for 10 years.

On those terms, the supply of customers would be almost unlimited, but Daiwa's Koichi Ishimura, deputy general manager for international finance, observed, "We have decided to do things slowly."

One reason, he explained, is that a sudden expansion of yen loans overseas would make it difficult for the Japanese government to issue its bonds, at even lower rates, in this country. Daiwa and three other leading investment houses have agreed with the ministry of finance to keep the lid on, an example of government-business cooperation that might be regarded as rare in western countries. Although the bankers and bureaucrats feud frequently here, there is a fundamental agreement among them about what's best for Japan and for the investment business.

That entwining of national interest and pursuit and profits also limits the export of capital in the form of yen loans, coveted by foreign borrowers because of their low-interest rates. Banks must, under government guidelines, give priority to supranational institutions or to governments of countries that import Japanese products or supply Japan with natural resources.

That cuts out many borrowers. "We get many requests but are forced to explain [to many customers] that they are not in the right category," said Hashimoto of the Bank of Tokyo. "There are more borrowers than we can take care of."

Despite all these restrictions, Japanese banks will play a much larger role in all financial fields in the 1980s, experts agree. Banks and investment houses already are helping recycle the Middle Eastern countries' oil dollars and the influx of that money has helped Tokyo's stock market become the second largest in the world in trading volume, behind only New York's.

The yen is destined to become a much more important international currency, used increasingly as a reserve currency and for settlements in foreign trade, the experts say.

"In the long run, say maybe five or 10 years, Tokyo will be another London," said Hayden of the Bank of America. "It's got everything. It has half the gross national product of Asia, the best telecommunications facilities. It won't dominate Asia in the same sense that London once dominated Europe but it will definitely be one of the big three along with Singapore and Hong Kong."