SHAH ALAM - Malaysia's former Prime Minister Mahathir Mohamad has pledged his support for the Free Anwar campaign, calling for the release of his once sworn enemy, imprisoned Parti Keadilan Rakyat (PKR) de facto leader Anwar Ibrahim.

Tun Dr Mahathir was attending the national congress of the opposition PKR on Sunday (May 21), which saw the relaunch of the Free Anwar campaign.

Dr Mahathir was seen signing the petition for the campaign while making his way out before being swarmed by reporters.

Dr Mahathir, however, cheekily avoided picking up the campaign placards, choosing instead to use his phone to photograph the cheering audience.

Speaking to reporters later, the 91-year-old former Umno top gun refused to acknowledge his involvement in prosecuting his former protégé by blaming his successor, current prime minister Najib Razak.

"It's not me who put him in jail, that's an old story. Najib is the one who put him (in jail)," he said.

Anwar, who served as Dr Mahathir's deputy prime minister from 1993 to 1998, was first jailed during the Mahathir administration amid allegations of sodomy and corruption. His PKR party was formed in April 1999 seven months after the sacking.

Dr Mahathir and Anwar met last September in a move to put the past behind them.

Anwar is currently serving a five-year jail sentence from 2015 for a sodomy offence.

At Sunday's event, Dr Mahathir also refused to answer whether Anwar should be nominated as the next prime minister should the opposition win the next general election.

"That's up to anyone," he replied.

Also present at the event was the president of Dr Mahathir's Parti Pribumi Bersatu Malaysia (PPBM) party, Mr Muhyiddin Yassin.

The PPBM, which Dr Mahathir chairs, was formed in August last year months after the former premier left Umno. Together with the PKR, the two parties are members of the Pakatan Harapan opposition coalition, which also includes the Democratic Action Party and the Parti Amanah Negara.