Cape Town - An ANC motion of confidence in Parliamentary Speaker Dr Frene Ginwala - accused of bias and dereliction of duty - will be debated in the National Assembly on Thursday, with most opposition parties expected to vote against it.

Democratic Alliance (DA) Chief Whip Douglas Gibson said his party would oppose the motion of confidence "because we feel it is totally inappropriate to deal with a parliamentary crisis in this way".

The motion would lead to a weakening of parliamentary democracy and the Speaker.

However, Gibson ruled out any boycott or walkout by the DA, saying this would be "inappropriate".

He accused the ANC of applying the tyranny of the majority.

"A majority vote (by the ANC) will not alter the facts and it neither substantiates the serious allegations or refutes them."

On perceptions that if the DA voted against Ginwala this would be viewed as a motion of no confidence in her, Gibson said, "I don't care about perceptions. The fact is that we are saying the motion is wrong."

The DA has drafted an opposing motion to the ANC's, calling for what most opposition parties and Ginwala herself favour - the establishment of a multiparty committee to examine claims that she interfered in the probe into the arms deal.

Other opposition parties, including the United Democratic Movement and the Pan Africanist Congress, have also been approached to support the DA.

Ginwala is on record as saying that she will not attend, preside over, or participate in Thursday's debate.

The 102-minute debate will be introduced by ANC Chief Whip Tony Yengeni -who has himself denied allegations of impropriety in the arms deal - with senior government MPs including Pallo Jordan, Public Service Minister Geraldine Fraser-Moleketi and Jeremy Cronin lined up to speak.

The ANC motion of confidence was prompted by a letter from UDM President Bantu Holomisa in which he accused Ginwala, of among other things, dereliction of duty and bias, because of her interventions in Parliament about the arms probe.

Ginwala has sent a lawyer's letter demanding an apology from Holomisa for his alleged defamatory remarks, but the UDM leader has refused.

Despite requests that the UDM should have more time to speak, the party will be confined to four minutes, its Chief Whip Cedric Frolich said.

"We'll take it in our stride. We'll settle for the four minutes and in that restricted time well get our message across."

A decision would be made at Thursday's caucus meeting about whether Holomisa or another MP would speak in the debate and whether the DA's amendment to the motion would be supported.

Inkatha Freedom Party Chief Whip Koos van der Merwe said his party would also decide its position at Thursday's caucus meeting.

IFP MP and chair of the public accounts committee, Dr Gavin Woods, has also refused to apologise to Ginwala after earlier questioning her role in the investigation.

He was among the first to accuse Ginwala of bias and said her interventions had by design sidelined his committee in the arms probe.

PAC Chief Whip Patricia de Lille said her party would also oppose the motion as it supported the establishment of a multiparty committee to investigate the allegations against the Speaker.

The amended motion calls for the committee to report back to Parliament by June 29.

With acknowledgement to Sapa and News24.