About 1,600 Rohingya and Bangladeshi refugees have landed illegally in Malaysia and Indonesia in the last two days, apparently after human traffickers abandoned their virtual prison ships and left them to fend for themselves, officials said on Monday.

One group of about 600 people arrived in the Indonesian coastal province of Aceh on four boats on Sunday, and at about the same time 1,018 others landed in three boats on the northern resort island of Langkawi. The Rohingyas, who are Muslim, have for decades suffered from discrimination in Buddhist-majority Myanmar, which considers them illegal settlers from Bangladesh.

Attacks on the Rohingyas by Buddhist mobs in the last three years have sparked an exodus to nearby countries.

Langkawi island deputy police chief Jamil Ahmed said that the group picked up Sunday comprised 865 men, 101 women and 52 children. Police found a big wooden boat trapped in the sand in shallow waters at a beach in Langkawi, capable of holding 350 people, he said. This meant there were at least two other boats but they have not been located yet, he said.

Jamil said a Bangladeshi man told police that the boat handlers gave them directions on where to go once they reached the Malaysian shores, and escaped in other boats.

They have not eaten for three days and most of them were weak and thin, Jamil said.

"We believe there may be more boats coming," Jamil said.

When the four ships neared Indonesia's shores early on Sunday, some passengers jumped into the water and swam, said Steve Hamilton, of the International Organization for Migration in Jakarta, Indonesia's capital.

They have been taken to a sports stadium in Lhoksukon, the capital of North Aceh District, to be cared for and questioned, said Lieutenant Colonel Achmadi, chief of police in the area, who uses only one name.

Sick and weak after more than two months at sea, some were getting medical attention. "We had nothing to eat," said Rashid Ahmed, a 43-year-old Rohingya man who was on one of the boats. He said he left Myanmar's troubled state of Rakhine with his eldest son three months ago.

An estimated 7,000 to 8,000 people are being held in large and small ships in the Malacca Strait and nearby international waters, said Chris Lewa, director of the Arakan Project, which has monitored the movements of Rohingyas for more than a decade. She added that crackdowns on trafficking syndicates in Thailand and Malaysia have prevented brokers from bringing them to shore.