KUALA LUMPUR (Reuters) - Leaders of Malaysia’s ruling party have condemned violence that erupted at a forum where former prime minister Mahathir Mohamad was speaking, as political tension rises ahead of a general election that could be called in coming months.

FILE PHOTO: Former Malaysian prime minister Mahathir Mohamad speaks during an interview with Reuters in Putrajaya, Malaysia, March 30, 2017. REUTERS/Lai Seng Sin/File Photo

One opposition leader accused Prime Minister Najib Razak of “gangsterism” to keep Mahathir quiet after some people at the Sunday meeting threw shoes, chairs and flares at Mahathir, who has made it his mission to unseat Najib over his handling of the a multi-billion dollar scandal involving a state fund.

Mahathir, 92, was not hurt, his aide said.

Deputy Prime Minister Ahmad Zahid Hamidi said differences of opinion did not give anyone license to act violently.

“As a country that practices democracy, such an incident should not have happened,” Ahmad Zahid was quoted as saying in the Star daily newspaper on Monday.

Mahathir, who served as prime minister for 22 years until he stepped down in 2003, chairs a fractured opposition alliance hoping to unseat the long-ruling government coalition in election due by next year.

Mahathir has offered to head a government again if the opposition wins.

Some opposition leaders allied with Mahathir accused Najib of orchestrating the violence. A deputy president of the People’s Justice Party, Azmin Ali, said in a statement the prime minister had resorted to “gangsterism”.

A senior member of Najib’s United Malay National Organisation, who is also a government minister, Salleh Said Keruak, said such accusations were “unhealthy” for politics.

“Remember that gangster politics is not part of our political culture,” Salleh said in a statement.

Another government minister, Khairy Jamaluddin, condemned the violence in a Twitter message saying it “cannot be tolerated”.

Media reported that police had detained two people.

Mahathir has been a prominent critics of his former protege Najib over the scandal-ridden state fund 1Malaysia Development Berhad (1MDB).

Najib denies wrongdoing.

1MDB is the subject of money-laundering investigations in at least six countries. The U.S. Justice Department alleged in civil lawsuits that about $4.5 billion of funds were misappropriated from the fund.

The U.S. Justice Department said in its latest court filing on Thursday it was conducting a criminal investigation of 1MDB and asked for a stay on civil lawsuits it had filed to seize assets allegedly bought with money stolen from the fund.

Najib denied taking money from 1MDB after it was reported that investigators traced nearly $700 million to his bank accounts. Authorities cleared him of any wrongdoing, saying the money was a donation from Saudi Arabia.