The lawmaker who vouched for the group which ambushed Shah Alam MP Khalid Samad within the parliament compound must be held responsible, said Deputy Home Minister Nur Jazlan Mohamed.

Describing the incident as a serious security breach in a restricted area, he did not rule out probing the matter under anti-terrorism laws.

"The general rule about inviting visitors into parliament is that they must be sponsored by a MP.

"If these people were actually invited by a MP into this area to cause bodily harm, distress, the MP should also be brought to the rights and privileges committee," he told reporters when met at the parliament lobby today.

Khalid was ambushed by about a dozen people this morning outside the parliament lobby. However, he was protected by parliament security officers.

The group was allegedly from Pasir Salak, Perak and expressed anger at Khalid for calling their MP, Tajuddin Abdul Rahman, 'sial'.

Asked if the group would be investigated under the Security Offences (Special Measures) Act (Sosma), Nur Jazlan said they would probe it under regular laws first.

Asked further on whether they would be probed for terrorism, he replied: "That may be, if there is cause for them to be investigated under that."

He said that security in parliament needs to be improved, and that he was "not happy" that parliament was violated in such a manner.

"This is a restricted area where the security forces managing this area can take extreme action including shooting intruders, especially those that threaten bodily harm and the peace.

"What if a terrorist had slipped into this area and committed a terrorist act?

"What happened today is exactly the same but without any weapons being used," he added.

He said the chief government security officer (CGSO) in charge should have taken preventive measures and not allow the group into the parliament grounds, let alone near the House chamber.

Khalid said he had been informed by parliament security about the group's presence upon arriving at the Parliament gates.