Inspector-general of police Khalid Abu Bakar has said the face-off between Umno Youth and Parti Pribumi Bersatu Malaysia (Bersatu) Youth members at PWTC on Tuesday is a "petty incident" and an embarrassment to all involved.

He also told reporters at Bukit Aman that at least 11 individuals have been called to assist in police investigations on the incident.

"Let them (police) investigate first. That kind of ruckus is (a) petty (matter)," he said after attending the force's monthly assembly.

Asked for further details on the individuals, Khalid, however, said there is no need for him to mention any names.

At the same time, he also urged all quarters to start acting like mature adults.

"We are all adults, not little children anymore. We have to show our maturity.

"To be involved in such incident, to me is shameful," he said.

A group of some 100 Umno Youth members had prevented the Bersatu Youth delegation, comprising some 30 members from entering PWTC, which is also the Umno headquarters, to hand over an invitation for their "Nothing to Hide 2.0" forum next month.

The police had ordered both groups to disperse and Bersatu Youth members had subsequently lodged a report at the Dang Wangi district headquarters.

Bersatu Youth exco member Ashraf Mustaqim Badrul Munir had also alleged that he was punched during the incident.

On another matter, Khalid declined to reveal further details regarding a man who was arrested for allegedly threatening lawyer Siti Kasim.

"Wait for him to be charged. If he is to be charged," he said when asked to elaborate on the reported arrest.

Kuala Lumpur police chief Amar Singh yesterday confirmed the arrest and said the man has been remanded for three days.

Siti had earlier lodged a police report over death and rape threats allegedly made against her online, following an article on her support of the lesbian, gay, transgender and bisexual community. 

She said there were also threats to behead her and attack her with acid.