WASHINGTON (AP) _ Sen. Joseph Lieberman, D-Conn., said in Israel on Thursday that his visit to Saudi Arabia and Kuwait earlier in the week marked the first time that either Arab nation had accorded entry to a visitor with an Israeli stamp in his passport.

''With that simple, but significant act of stamping my passport, Saudi Arabia and Kuwait have removed another obstacle from the road toward peace in the Middle East,'' Lieberman said at a news conference in Tel Aviv.

A text of his opening remarks at the news conference was released by Lieberman's office on Capitol Hill.

In the past, people whose passports bear evidence of travel to Israel have been turned away by Arab nations - a practice related to their longstanding economic boycott of Israel. Americans and others have gotten around the restriction by carrying a separate passport for Israel.

''This is the first time this has happened, but it is clearly not the last,'' Lieberman said, adding he hopes the gesture by Saudi Arabia and Kuwait ''will help build confidence among the nations of this region to take further steps to build trust until peace is secured.''

In Washington, a source close to the Saudi government confirmed the precedent - one accented by the fact that Lieberman is Jewish - saying it marked a significant policy change in Riyadh. But this source, who asked not to be identified, said the shift was not being publicly announced because of possible adverse domestic reaction in Saudi Arabia.

The State Department said that while entry regulations were ''a sovereign matter'' it had encouraged Saudi Arabia and other Arab states to stop denying passports to travelers whose passports were processed in Israel.

''In this regard, Sen. Lieberman's visit is a welcome development,'' the department said in a brief statement.

Lieberman, on a trip to the Middle East to examine progress in fighting oil well fires in Kuwait, arrived in Riyadh on Monday and went to Kuwait on Wednesday.

A celebrated instance occurred in March, when another Jewish senator, Frank Lautenberg, D-N.J., was denied entry to both countries during a trip to the Persian Gulf region. Lautenberg was forced to get a separate passport from the State Department, and then was granted entry visas.

Lautenberg later pushed legislation that would have banned the practice of dual passports for travel in the Middle East.

The Saudis have proposed that the Arab economic boycott of Israel be ended in exchange for a halt to Israeli development of new Jewish settlements in occupied Palestinian territory.

Lieberman has been meeting in recent months Prince Bandar bin Sultan, the Saudi ambassador to Washington, and the trip evolved from those meetings, according to the source who declined identification.