Pope John Paul II ended a 12-day South American tour on his 68th birthday and left for Rome, telling Paraguayans to reconcile their differences and build a better nation.

"The key to unity, reconciliation and brotherhood is in the Scriptures," the pontiff said at an airport farewell ceremony Wednesday attended by authoritarian President Gen. Alfredo Stroessner, 75, the Western Hemisphere's longest-ruling head of state."By building a Christian nation and being faithful to your genuine roots, you can build a Paraguay of tomorrow," said John Paul, who early in the visit preached respect for human rights and civil liberties to Stroessner, in power since a 1954 coup.

Stroessner, bidding the pope goodbye, said the visit had been a "source of joy and hope" for Paraguay, which he described as "a pluralistic and democratic society . . . without terrorism . . . and enjoying full freedom within a state of law."

Most outside observers regard the nation of 3.8 million people as a dictatorship.

John Paul's trip, his 37th since becoming pope in 1978 and the ninth to Latin America, took him from tiny Uruguay on the Atlantic coast to Bolivia, high in the Andes, Peru on the Pacific and landlocked, semi-tropical Paraguay.

The pontiff ended his trip at a giant youth rally where he was serenaded with "Happy Birthday" sung in his native Polish and in Guarani, the Indian language spoken along with Spanish by most Paraguayans.

"I feel young, especially when I'm with young people," the pope told the 100,000 youngsters.