The Malaysian-owned Manyplus 12 was towing the Hub 18 barge with 138 containers.
It had left Sibu in Sarawak for Port Klang and was scheduled to arrive on 13 June, the Recaap reporting centre said.
Highline Shipping last contacted the master on 9 June when the vessels were west of Tanjung Datu.
The crew comprises 11 Indians, Malaysians and Myanmarese.
