The Anak Selangor Fans Club (ASFC) has criticised those who carried a banner calling on Prime Minister Najib Abdul Razak to quit during the recent Malaysia Cup final.

Speaking to Malaysiakini , its president Mohd Faizal Wahid said sporting events should not be politicised.

"ASFC is investigating the banner. We found that it is not by our members. If it is (ASFC members who are responsible), we will take action.

"In sports, we should set aside political ideologies and celebrate the sport," Faizal added.

The banner with the words 'Undur Najib' appeared where Selangor fans were seated during last Saturday's match with Kedah at the Shah Alam Stadium.

Malaysiakini learnt that the banner was held up briefly, when the national anthem was played before the kick-off.

Expressing regret over the incident, Faizal said sports should serve as a platform to unite people, not be exploited to spark off controversies.

He added that those responsible knew that their action would garner attention, since it was the final match for the Malaysia Cup.

Photographs of the banner had gone viral on the social media, with even former prime minister Dr Mahathir Mohamad pouncing on the incident.

In a blog post yesterday, Mahathir said thousands of Malaysians, including football fans, want Najib to relinquish his post - but the authorities were only targeting him.

The police are investigating Mahathir for over his allegation that Umno grassroots leaders have taken bribes.

He could also face investigations for stating that Najib should be arrested under the Special Offences (Special Measures) Act (Sosma).

Mahathir has accused Najib of numerous misdeeds in relation to 1MDB and the RM2.6 billion political donation.

The prime minister has denied any wrongdoing and described the allegations as a conspiracy to topple him.