BEIRUT, Lebanon (AP) _ Moslem militiamen stopped a papal envoy from driving to south Lebanon's main Christian town Thursday, Christian-controlled radio and television stations reported.

The Rev. Celestino Buhigas arrived over the weekend on what the Vatican described as a humanitarian mission to show the concern of Pope John Paul II for the suffering in Lebanon, where a decade-long sectarian civil war has taken an estimated 100,000 lives.

He met on Wednesday with President Amin Gemayal, a Maronite Catholic, and said he intended to remain in Lebanon for ''a few months.''

The radio station Voice of Lebanon and Channel 12 television gave this account of the attempt to reach Jezzine:

A Lebanese army helicopter took Buhigas from Christian east Beirut to the coastal region of Zahrani in south Lebanon, where the population is predominantly Shiite Moslem.

The envoy drove in a motorcade from the army's garrison at Zahrani's oil refinery to the outskirts of Sidon on its way to Jezzine, 15 miles to the northeast, Moslem militiamen manning a checkpoint at the southern entrance to the predominantly Sunni Moslem city prohibited Buhigas from proceeding.

Buhigas returned to Zahrani and flew back to Beirut three hours later.

Jezzine had been swollen by thousands of Christian refugees who fled a Moslem offensive last April that drove them from a string of coastal villages east and northeast of Sidon.

It and the surrounding hills are controlled by the South Lebanon Army, a mainly Christian militia supported by Israel. The SLA clashed on Thursday with Moslem militiamen around the Christian mountain stronghold of Kfar Falous halfway between Sidon and Jezzine, as it does almost daily.

The new papal initiative followed threats by the SLA commander, retired Lebanese Army Gen. Antoine Lahd, to push toward Sidon, and Moslem counter- threats to storm Jezzine.

Last July, John Paul sent French Cardinal Roger Etchegaray to Lebanon.

Etchegaray, who is president of the Vatican's Justice and Peace Commission to Lebanon, met with Christian and Moslem political and spiritual leaders. He spent several days in Jezzine.