BN elected representatives are not permitted to join Bersatu en masse and will instead be subjected to vetting, said Bersatu chairperson Dr Mahathir Mohamad.
He said they would have to first leave their party and become independents before their applications would be considered.
In addition, they may only join one at a time so existing Bersatu members don't become outnumbered by the defectors.
“If they leave the party and become independent, and they support the government, and they appeal on bent knees (saying) that they want to join us, we may consider.
“Not those people who’ve got a charge against them […] We will see the quality of the people who want to join; not all of them are guilty.
“Those who had been leaders who openly and outspokenly supported the theft, that won’t do. But for ordinary members who just want to be elected representatives and are not subject to any (legal) action, we will consider that.
“There would be no such thing as automatic joining,” he told a press conference after chairing the Pakatan Harapan presidential council in Putrajaya today.
Previously, Bersatu supreme council member A Kadir Jasin claimed there had been rumours that 40 Umno MPs would leave the part, and some of them would join Bersatu.
This prompted concern from Bersatu allies and civil society groups.
DAP chairperson Tan Kok Wai had said it is unhealthy for Harapan parties to accept former Umno MPs, while Amanah deputy president Salahuddin Ayub urged for caution on the move.
A group of civil society groups issued a joint statement urging Mahathir not to repeat his 1988 'mistake' of destroying Umno by manipulating government machinery and then setting up ‘Umno Baru’ for his loyalists to cross over to.