Malaysia has denied entry to a boat carrying about 200 Rohingya due to coronavirus fears, the air force said, after news emerged this week that scores died on another crowded vessel.
Activists are now fearful that large numbers of Rohingya, a persecuted Muslim minority from mostly Buddhist Myanmar, may be trapped on boats at sea and unable to reach other countries.
The latest developments have sparked concerns of a repeat of a 2015 crisis when many Rohingya died at sea after Southeast Asian nations turned their boats back, following a crackdown on traffickers that threw established smuggling routes into chaos.
In the latest incident, the Rohingya boat was spotted Thursday by a Malaysian air force jet off the north-western island of Langkawi and then intercepted by two navy vessels backed by a helicopter.
Malaysian sailors gave the Rohingya food before escorting them out of the country's waters, the air force said.
"With their poor settlements and living conditions... it is strongly feared that undocumented migrants who try to enter Malaysia either by land or sea will bring (Covid-19) into the country," said an air force statement late Thursday.
It added that "maritime surveillance operations will be intensified."
The development signalled that Malaysia, which is under a nationwide lockdown to combat the spread of the virus after recording more than 5,000 cases and 80 deaths, is toughening its stance to deny Rohingya entry.
While relatively few boats carrying the minority have arrived in Malaysia since the 2015 crisis, some have been allowed into the country. Earlier this month, 202 Rohingya landed in Langkawi and were detained.
