Update 2 - Adds Simon Busuttil, PL's comments - Opposition MPs walked out of the House of Representatives this evening after the Speaker delivered a ruling finding Opposition leader Simon Busuttil prima facie in breach of privilege.

The Speaker had been requested to rule yesterday by Prime Minister Joseph Muscat.

Dr Muscat complained that the leader of the opposition had accused him of interfering in police investigations involving John Dalli. He denied that that was the case and asked Dr Busuttil to substantiate his comment or withdraw it.

Dr Busuttil said he was sticking to his comment as it was a political judgement based particularly on sworn testimony in court by former Police Commissioner John Rizzo.

In his ruling today, the Speaker, Anglu Farrugia found the leader of the opposition in breach of privilege and referred the case to the Privileges Committee.

The deputy leader of the opposition, Mario de Marco, said amid loud interruptions from government MPs that MPs should have freedom of expression on the basis of their political judgements in the House and it was a shame that the prime minister had felt offended by such comments.

Government MPs protested that Dr de Marco was abusing, but the Speaker said he had allowed a brief statement, but no one could comment on his ruling.

The Nationalist MPs then walked out of the chamber. Parliamentary questions by Nationalist MPs were not put.

In his ruling the Speaker said he had considered that freedom of expression was fundamental to democracy and it had to be careful before deciding on a breach of privilege. The Chair was not a court, not could it decide on the facts of the case.

He noted that Standing Orders provided that no MP could use offensive or unbecoming language against the character or infer any bad motive on any MP.

He noted that the Chair had offered Dr Busuttil the opportunity to withdraw his comments but he refused to do so on the basis of what he described as a political judgement.

Dr Farrugia quoted a ruling by Speaker Joseph Flores in 1955 that an MP had to assume responsibility for his comments and had to be prepared to substantiate it.

The Speaker said he had also considered what was declared by former Commissioner Rizzo.

See Speaker's ruling in full by clicking on pdf below.

BUSUTTIL: RULING WILL BE CONTESTED

In a press conference Dr Busuttil said the Nationalist MPs had walked out from the Chamber in protest because the government was trying to gag the Opposition.

He said the Opposition would contest the ruling in Parliament and, if necessary, before the Constitutional Court and the European Court of Human Rights because democracy was being undermined.

Asked what evidence he had that the prime minister had interfered in the police work, Dr Busuttil said he had every right to reach a political judgement. He noted that the statement he had made in Parliament had also been made outside. It was surreal that he could not say in parliament what he could say outside, when it was usually the other way around.

PL: OPPOSITION INCREASINGLY ISOLATED

The Labour Party said Dr Busuttil was continuing to isolate the Nationalist Party through his negativity. People could no longer understand the hurried decisions he was taking.

Dr Busuttil had made baseless allegations which he was not able to substantiate, and thus embarrassed the PN. 

It was evident, the PL said that some Nationalist MPs with more experience had disagreed with today's action.