KUALA LUMPUR - A landmark law that bars MPs from switching political parties comes into effect on Wednesday.

The law, aimed at preventing political defections, is a key condition of a confidence and supply agreement (CSA) inked by Prime Minister Ismail Sabri Yaakob's administration and the opposition Pakatan Harapan (PH) in September last year.

Speaking at a news conference in Parliament on Tuesday, de facto law minister Wan Junaidi Tuanku Jaafar was quoted by The Star news daily as saying that the King has agreed that the anti-party hopping law will take effect on Wednesday.

The law was gazetted on Sept 6.

Lawmakers in July unanimously passed the Bill, more than two years after defections collapsed the PH federal government in 2020 and sparked a period of political instability and two changes in government.

Under the new law, a recall election or by-election will be triggered when an MP quits or jumps party. MPs elected as independents will also lose their seats if they formally join any party.

The Bill was initially tabled in April, but a vote was deferred after MPs voiced concerns over some of its wordings.

The Bill later went to a bipartisan Parliamentary Special Select Committee, which spent over two months refining it.

As it sought a broad buy-in from all the parties in Malaysia's fragmented political landscape, key exceptions were made.

MPs fired from their parties will not need to vacate their seats.

En bloc defections by a party - like that of Parti Pribumi Bersatu Malaysia, whose departure from the PH government had led to its collapse - are also not covered under the new law.

The CSA has helped Datuk Seri Ismail lead an awkward coalition of political rivals with a single-digit majority since August last year, after his predecessor Muhyiddin Yassin resigned as prime minister after only 17 months on the job. Mr Ismail is the third Malaysian PM since the 2018 elections.