MANSA, ZAMBIA -- A river barge crowded with passengers hit a sandbar while the pilot apparently was asleep, and the vessel sank, drowning 23 people and leaving more than 300 others missing and feared dead, Zambian police said yesterday.

The accident occurred early Sunday about 400 miles north of Lusaka on a remote stretch of the Luapula River, which forms the frontier between Zambia and Zaire, but details were not available until yesterday because of poor communications, according to Baldwin Kaila, police chief of Luapula Province.

Of the estimated 470 Zairians and Zambians on the barge, more than 300 were still missing and believed drowned, and only 23 bodies had been recovered so far, Kaila said. Most of those who survived -- about 80 passengers -- were traveling on the top deck and managed to swim to safety, he said. The police chief said the pilot, who apparently was sleeping when his barge hit the sandbar, had surrendered to authorities.

The death toll in a train-truck collision in Zaire, meanwhile, rose to 128 with the recovery of three more bodies. The collision occurred Thursday when a trailer-truck struck the train at an unguarded crossing near the Zambian border. It was believed to be the worst train wreck ever in Africa.