TUNIS -- Their waists are thicker, their hair often gray and thinner, but the uprising in the West Bank and Gaza Strip has reinvigorated the veterans around chairman Yasser Arafat who for a generation have helped him run the Palestine Liberation Organization.

Not since Israeli arms evicted them from Beirut in 1982 -- and set in motion a series of tribulations and humiliations -- have these survivors exuded such self-confidence and sense of purpose.

Thanks to Israel's automatic dial telephone system -- and clandestine channels -- they claim to be in "minute-to-minute" touch with the underground leadership inside the occupied territories, receiving and dispatching everything from policy working papers to daily updated reports on the names, ages and hometowns of Palestinians killed, wounded or arrested in clashes with Israeli security forces.

In interviews last week, senior PLO officials noted that Israeli and Arab leaders have stopped questioning their organization's control of the situation inside the territories occupied by Israel in the 1967 war. They assert that PLO money, advice and instructions have done much to perpetuate the 10-week-old uprising and disproven claims by U.S. officials and others that the PLO has lost its influence and relevance.

Yet, Palestinians thinking ahead say the future seems strewn with uncertainties that are likely to take Palestinian nationalism in more radical directions.

"If the uprising succeeds -- and that is still not clear," one Palestinian official in his forties said, "then and only then will there be a new political leadership inside."

"Right now the leadership inside is PLO, for these young men and the PLO grew up together in the wake of the 1967 defeat," he said.

"But those inside are building a new organization in the middle of crisis. Something new is in gestation," he said. "Its leaders are our sons, but they are men."

"If they win the present military phase for control of the refugee camps and urban centers," he added, "they will keep Arafat as the symbol of Palestinian nationalism, but political decision-making will be in their hands."

Based on a close reading of exchanges between the outside leadership and the United National Committee for the Uprising inside, he predicted such a new leadership within the territories would radicalize Palestinian nationalism.

Already those inside, especially West Bank Arabs -- long considered the most moderate Palestinians -- are openly critical of the PLO's relations with Egypt and Jordan, he noted. Young radical leaders also vetoed the hopes of more moderate Palestinians to meet Secretary of State George P. Shultz during his visit to Israel this week.

Some officials of moderate Arab countries call attention to this emerging radical trend. They fear that the anger of Palestinians inside the occupied territories may soon be directed toward their governments, accused of doing nothing to aid the protests.

A senior Tunisian official remarked: "If the PLO did not exist, the Americans and moderate Arabs would be well advised to invent it.

"The Americans should be thanking their lucky stars for these fat and balding PLO leaders they spend so much of their time writing off as irrelevant, for these men have international experience, they know Israel is a reality backed by very strong forces.

"They know how to negotiate more than some wild-eyed 28-year-old or an Islamic fundamentalist fanatic who thinks everything is in God's hands," the Tunisian official said. "Arafat's strategy is still to cut a deal, but it is getting harder and harder for him."

Khalil Wazir, better known as Abu Jihad, who runs PLO operations with the occupied territories, said that far from resenting potential rivals, "we are proud to let this young generation be the vanguard."

His colleague, Salah Khalaf, the security chief known as Abu Iyad, described the young stone-throwers as "better than our generation," which founded Fatah, the mainstream PLO group, and took over the PLO itself after the 1967 war.

He said growing up under the Israeli occupation had simplified their thinking, while his generation had been corrupted by dealing with "Arab regimes and intelligence organizations, which we thought was the way to fight for Palestine."

He said he was impressed by a working paper on escalating the disturbances recently sent from inside the occupied territories. "They are highly conscious that victory inside should not be at the expense of those outside," he said.

Other senior PLO officials said the outside leadership sought to "broaden the outlook" of their counterparts inside, especially providing political slogans and demands for inclusion in communiques and tracts distributed in the West Bank and Gaza.

One official compared the outside leadership's role to that of a battalion commander who issues overall orders, but allows company and platoon commanders to use their own initiative.

The PLO leaders interviewed showed no signs of placing greater trust or hope in support from other Arab governments, whose worries over lower oil prices, the Persian Gulf war and fears about political tensions among their populations have dimmed their support for the Palestinian uprising in the occupied territories.

But PLO officials said they were encouraged when Egyptian President Hosni Mubarak, who only recently infuriated Palestinians by asking them to stop demonstrating against the occupation for six months, last week said the U.S.-brokered Camp David formula for Palestinian autonomy was "a thing of the past."

Only radicals still hope to persuade Cairo to break relations with Israel, Syria to relent in its opposition to the PLO or Jordan to accept an enlarged PLO presence on its territory once again.

"We're still a far cry from the 1973 Arab-Israeli war," one official said, recalling the oil boycott that forced the United States, Western Europe and other industrialized states to take the Palestinian cause seriously.

Any hopes for new Arab backing for the Palestinian cause were dashed last month when an emergency meeting of Arab League foreign ministers here failed to pledge funds to help the PLO pay for burgeoning costs inside the occupied territories.

Nonetheless, some PLO officials insist that their overseas investments plus gifts from rich and poor Palestinians among the 3 million in the diaspora are sufficient to maintain a high profile among Palestinians living under occupation.

But others said lack of funds may explain why the PLO has so far avoided calling for massive civil disobedience, since anywhere from $30 million to $50 million a month might be required by the Palestinians if they were instructed to stop working in Israel.