A high-level Palestinian delegation was reported en route from Beirut to Tehran to offer help in freeing U.S. Embassy employes held hostage by militant Iranian militiamen.

The team was dispatched by Yassar Arafat, head of the Palestine Liberation Organization, in an apparent attempt to enhance the PLO's image as a respectable interlocutor for the United States for negotiations with Israel over the future of West Bank and Gaza. It was the latest in a series of gestures by the PLO chieftain designed to depict his organization in more moderate tones for U.S. and European

Leading the PLO envoys to Tehran was Hani Hassan, a long-time political adviser to Arafat who directs the newly opened office in Tehran. Hassan, who ordinarily resides in Tehran, was in Beirut following a trip last week to Lisbon with Arafat for a gathering of the Socialist International, where the Palestinian issue ws among the main subjects of discussion. He played a key role in counseling Arafat during the Lebanese civil war and is considered to be among the most experienced political operatives in the PLO.

PLO spokesman in Beirut were careful, to insist that the Palestinian mediators have been told that they are only to make themselves available to assist and were not carrying orders for direct intervention in the embassy siege.

This was seen as an effort to guard against irritating Iranian sensibilites, which could be jarred by seeing Arafat help protect American lives and thereby frustrate the plans of young Iranian Moslem zealots. In addition, the caution of PLO spokesmen had the effect of protecting the PLO mediation against the appearance of failure should the Tehran Embassy seizure end in disaster or stalemate despite PLOassistance.

Despite denials from Washington and PLO officials in New York, PLO sources here nevertheless hinted that the United States had requested their intervention on behalf of the captured Americans These claims of collaboration with the Carter administration also fit in with current PLO tacts of portraying the guerrilla leadership as a responsible political organization.

Similar Palestinian intervention was credited with helping persuade terrorists to release hostage and surrender during the recent takeover of the Eygptian embassy in Ankara, Turkey.

Since the departure of the shah and the installation of an Islamic Republic in Iran, the Tehran government has become one of the Plo's most ardent supporters. This was illustrated by the opening of the PLO office in Tehran soon after Ayatollah Ruhollah Khomeini's rise to power and Arafat's decision to assign one of his top advisers to head it.