A spate of recent incidents involving Iranian diplomats and alleged Iranian-trained terrorists arrested in the oil-wealthy Persian Gulf sheikdoms has given new urgency to these countries' plans for a regional security pact.

For the second time in less than two weeks, a high-ranking Iranian diplomat has been expelled from an Arabian peninsula country for allegedly promoting subversion of the local government.

North Yemen Tuesday declared the Iranian charge d'affaires persona non grata and announced that he had been caught in the act of distributing "anti-Yemeni leaflets."

Early last week, the top Iranian diplomat in the island state of Bahrain, Hassan Shushtari Zadeh, was expelled after authorities there arrested 60 persons who were said to have been Iranian-trained and preparing to launch Khomeini-style revolutions in the oil-rich Arab sheikdoms and kingdoms of the region.

The arrests and expulsion of Iranian diplomats have brought to the fore once again the issue of internal security among the six conservative Persian Gulf states and riveted their attention on Iran, rather than the Soviet Union or even Israel, as the major immediate source of instability.

The incidents raise the question of what assistance the U.S. Rapid Deployment Force could have been to these states had the alleged Iranian conspirators succeeded in taking over Bahrain, or more importantly one of the main oil-producing sheikdoms like the United Arab Emirates.

One of the objectives of the force is to shield these countries from foreign intervention, particularly Soviet, but the latest events suggest Iranian-fomented revolutions may be the main danger facing them now.

In any case, Bahrain and one other tiny sheikdom, Qatar, have turned to Saudi Arabia for help and signed bilateral security agreements with it in the wake of the mid-December arrests in Bahrain.

The Saudis, in turn, appear to have seized upon the occasion to promote their own plan for closer security cooperation among the six kingdoms and sheikdoms of the lower gulf--Bahrain, Qatar, the United Arab Emirates, Kuwait, Oman and Saudi Arabia.

Early this year, the six formed the Gulf Cooperation Council partly to deal with common internal and regional security problems. But differences of view, and in some cases suspicion of Saudi domination, have kept the council from adopting a security pact.

The defense ministers of the six are scheduled to meet in the Saudi capital, Riyadh, Jan. 18 to discuss the Saudi plan. The Saudis are proposing military and security cooperation among the six Persian Gulf states--without, however, having an integrated military command or force--both to defend the world's oil heartland and their own conservative governments without American or other outside assistance.

The latest Iranian scare seems to be a catalyst for agreement on the Saudi proposal.

Bahraini security sources have been quoted as saying that the 60 persons detained in the plot included 45 Bahrainis, 13 Saudis and one each from Oman and Kuwait. The sources said the 60 belonged to the Islamic Front for the Liberation of Bahrain and had received training in sabotage, terrorism and assassination in Iran.

Press reports said Bahrain learned of the alleged conspiracy when the security force in Dubai, one of the mini-sheikdoms in the nearby United Arab Emirates, arrested six members of the network and turned them over to Bahrain.

This seems to suggest the front also had members and activities in some of the other Persian Gulf states.

Iran has vehemently denied Bahraini allegations it had anything to do with the front or the group arrested in Bahrain, but neither the Bahraini government nor the other gulf council members seem to be taking the denials very seriously.

The Saudi interior minister, Prince Nayef, said his country had evidence it was among those targeted by the front. He rushed to Bahrain on Dec. 19 to sign a joint security agreement within days of the initial Bahraini announcement of the plot.

Nayef refused to give any details about the agreement but he did say Saudi Arabia stood ready to "do anything in its power, including sending security forces, to help out Bahrain or any other gulf state, if the need arises."

He also said Saudi Arabia expected all the other gulf council members to join the security pact "now that they all have become convinced beyond doubt that Iran is out to undermine their stability."

Bahrain's Interior Minister Mohammed Khalifa, on the other hand, was quoted by a Kuwaiti newspaper as saying it was time for the gulf council to establish its own rapid deployment force "to render urgent assistance when the need arises."

Other council members have made warm statements of support for Bahrain as well as sent their own security officials to interrogate the arrested front members.

The alleged resurgence of Iranian subversive activities in the Persian Gulf countries highlights the continuing revolutionary and religious zeal of the Khomeini government despite its internal difficulties and 15-month-old war with Iraq.

Ever since Ayatollah Ruhollah Khomeini ousted the shah in early 1979 and established a Shiite theocracy, Iranian religious leaders and the state-run radio have repeatedly urged the Arabs on the other side of the gulf to overthrow their "corrupt" monarchies and establish Islamic republics in the Iranian image.

Bahrain is a natural target for Iran's revolutionary government because half of its population of 300,000 belongs to the Shiite sect of Islam, which is the dominant one in Iran as well. In addition, Iran once laid territorial claim to the island, though the late shah dropped those claims.

While the Bahraini government did not specifically say those arrested were Shiites, it seems likely they were, particularly if they took training in Iran.

There are also Shiite communities in the other gulf states, providing Iran with a natural conduit into their societies.

Saudi Arabia, which has 150,000 Shiites living in its eastern province, has been locked in a war of words with the Khomeini government ever since it came to power, each accusing the other of Islamic heresy.

In September, there were clashes in the Saudi holy cities of Mecca and Medina between security forces and Iranian pilgrims shouting slogans and carrying pictures of Khomeini. Scores of Iranians were expelled.

Evidence of Iranian subversive activities in North Yemen is relatively new, however.

A government statement reported Thursday from the Yemeni capital of Sanaa said the Iranian charge had left the country.

An earlier statement said the diplomat had been warned before but had "escalated his attempts to create dissension and undermine the Yemen Arab Republic." The statement also said he had been declared persona non grata "after being apprehended while distribting anti-Yemen leaflets."

There was no indication what the leaflets said or how he had sought to create dissension, but presumably it involved calls to follow the example of the Iranian revolution.