In a quiet departure in Japanese diplomacy, Foreign Minister Shintaro Abe will leave Tuesday to visit Iran and Iraq in a bid to persuade the two countries to end their bitter conflict in return for the promise of greater Japanese economic and technical aid.

In a meeting with foreign reporters here today, Abe emphasized that he had "no intention whatsoever" of plaaying a direct mediating role in the Iranian-Iraqi war, but he added, "I will be strongly urging the two countries to seek an early end to their conflict."

Officials have carefully downplayed Abe's role as peacemaker, asserting that his visits are designed mainly to strengthen Japan's relations with Iran and Iraq, where Japan has sizable and growing economic stakes. According to diplomatic analysts, however, Tokyo intends to use its economic leverage quietly to impress on its Western allies a willingness to play an enhance global role.

This scenario, they point out, snaps neatly into Prime Minister Yasuhiro Nakasone's oft-stated aim to formulate a more assertive diplomacy.

Abe also will visit Romania, Bulgaria and Turkey during his 13-day trip.

Japan, which supported the U.S.-led embargo after Iran seized American hostages in 1979, has been particularly eager to improve its ties with Tehran. Japanese companies have developed lucrative markets in Iran for passenger cars, trucks, steel, textiles and have commercially developed "dual-usse" hardware important to Iran's war effort.

Japanese exports so far this year, officials said, have already exceeded $1 billion, compared to about $950 million in all of 1982. Japan's purchases of Iranian crude oil have risen sharply in recent months and amount to roughly 10 percent of the country's total oil supplies. Japan is now the largest purchaser of Iranian oil.

The biggest obstacle in two-way ties was overcome in May, officials said, when Tehran agreed to shoulder all future costs needed to complete a $3.5 billon petrochemical plant being built at Bandar Khomeini as a joint venture with Mitsui & Co., a leading Japanese trading company.

In the past decade, annual two-way trade with Iraq has grown nearly 67-fold to $ 3.5 billion, despite curtailment of Iraqi oil sales because of the war. Between 1979 and 1981, Iraq accounted for more than one-fifth of all Japanese overseas plant orders, making Baghdad by far the best foreign customer of Japanese construction companies.

Apart from the obvious economic incentives for Japan to immprove its relations with both countries, analysts here said Tokyo's favored position with them can be useful in efforts to promote Japan's self-styled "peace diplomacy."

"It will not be possible to persuade Iran and Iraq that they are fighting a futile war," said diplomatic commentator Kamiya Fuji. "But what Japan can do is to establish a framework for peace by using its economic and political impact. In that regard, Japan may be more influential than either the United States or Europe."

Despite speculation in the Japaese press that the United States has quietly asked Japan to try to mediate the Iranian-Iraqi dispute, Abe said today he would not "in any way represent the West." However, Abe said he was "fully aware we must contribute to the peace of the world in a manner commensurate with Japan's position."

Abe said Japan would not offer "a carrot" to either side. Officials suggested, however, that Tokyo is prepared to offer some economic incentives, including the promise of stepping up the flow of technology and agreeing to bring more technicians to train in Japan.

"We know our constraints," said a Foreign Ministry official. "We are not in the habit of swinging a big bludgeon of economic leverage." But, he went on, "our readiness to do more when the war ends will certainly be one element" in the thinking of leaders in Iran and Iraq. Tokyo's Envoy to Ask End of Iran-Iraq War By Tracy Dahlby Washington Post Foreign Service

TOKYO, July 28--In a quiet departure in Japanese diplomacy, Foreign Minister Shintaro Abe will leave Tuesday to visit Iran and Iraq in a bid to persuade the two countries to end their bitter conflict in return for the promise of greater Japanese economic and technical aid.

In a meeting with foreign reporters here today, Abe emphasized that he had "no intention whatsoever" of playing a direct mediating role in the Iranian-Iraqi war, but he added, "I will be strongly urging the two countries to seek an early end to their conflict."

Officials have carefully downplayed Abe's role as peacemaker, asserting that his visits are designed mainly to strengthen Japan's relations with Iran and Iraq, where Japan has sizable and growing economic stakes. According to diplomatic analysts, however, Tokyo intends to use its economic leverage quietly to impress on its Western allies a willingness to play an enhanced global role.

This scenario, they point out, snaps neatly into Prime Minister Yasuhiro Nakasone's oft-stated aim to formulate a more assertive diplomacy.

Abe also will visit Romania, Bulgaria and Turkey during his 13-day trip.

Japan, which supported the U.S.-led embargo after Iran seized American hostages in 1979, has been particularly eager to improve its ties with Tehran. Japanese companies have developed lucrative markets in Iran for passenger cars, trucks, steel, textiles and have commercially developed "dual-use" hardware important to Iran's war effort.

Japanese exports so far this year, officials said, have already exceeded $1 billion, compared to about $950 million in all of 1982. Japan's purchases of Iranian crude oil have risen sharply in recent months and amount to roughly 10 percent of the country's total oil supplies. Japan is now the largest purchaser of Iranian oil.

The biggest obstacle in two-way ties was overcome in May, officials said, when Tehran agreed to shoulder all future costs needed to complete a $3.5 billion petrochemical plant being built at Bandar Khomeini as a joint venture with Mitsui & Co., a leading Japanese trading company.

In the past decade, annual two-way trade with Iraq has grown nearly 67-fold to $ 3.5 billion, despite curtailment of Iraqi oil sales because of the war. Between 1979 and 1981, Iraq accounted for more than one-fifth of all Japanese overseas plant orders, making Baghdad by far the best foreign customer of Japanese construction companies.

Apart from the obvious economic incentives for Japan to improve its relations with both countries, analysts here said Tokyo's favored position with them can be useful in efforts to promote Japan's self-styled "peace diplomacy."

"It will not be possible to persuade Iran and Iraq that they are fighting a futile war," said diplomatic commentator Kamiya Fuji. "But what Japan can do is to establish a framework for peace by using its economic and political impact. In that regard, Japan may be more influential than either the United States or Europe."

Despite speculation in the Japanese press that the United States has quietly asked Japan to try to mediate the Iranian-Iraqi dispute, Abe said today he would not "in any way represent the West." However, Abe said he was "fully aware we must contribute to the peace of the world in a manner commensurate with Japan's position."

Abe said Japan would not offer "a carrot" to either side. Officials suggested, however, that Tokyo is prepared to offer some economic incentives, including the promise of stepping up the flow of technology and agreeing to bring more technicians to train in Japan.

"We know our constraints," said a Foreign Ministry official. "We are not in the habit of swinging a big bludgeon of economic leverage." But, he went on, "our readiness to do more when the war ends will certainly be one element" in the thinking of leaders in Iran and Iraq.