Deputy Provincial Commissioner Mzwandile Petros told a hastily called media briefing at provincial police headquarters in Cape Town on Thursday night that a 42-year-old coloured male was arrested at a house in Mitchell's Plain at 5am.

His arrest followed the release of identikits of the massacre suspects by the police investigation team earlier this month.

The man was questioned by the team and he later made a full confession before a magistrate.

Police acting on the further information, arrested a 26-year-old white male at his place of employment at the Victoria and Alfred Waterfront at 8.15pm.

After months of speculation in the media, Petros said the motive for the brutal attack has been established as robbery.

Both men will appear in the Cape Town Magistrate's Court on Monday.

Asked whether further arrests were likely, Petros said: "The investigation is continuing and it depends on what comes out of the second suspect. I cannot rule it out."

Police could not reveal what the two men did for a living.

However, Petros said the 26-year-old suspect lived in the Sea Point area where the attack took place.

Petros credited the six-man investigation team, that was set up under Superintendent Mike Barkhuizen to probe the killings, for Thursday's arrests.

Petros thanked the team for their "outstanding devotion to duty and the sacrifices made by them and their families in the past few weeks".

"It is impossible to put into words the amount of time and effort demanded from investigators in a case such as this," he said.

The head of police detectives in Cape Town, Commissioner Andre du Toit, told journalists it was "difficult" to give further information at this stage but he promised that the media would be kept informed of new developments.

Journalists pressed du Toit on the circumstances surrounding the massacre and the arrests.

Du Toit said: "We have given you fresh news and we are busy with the investigation. I can't answer some of the questions."

Shortly after the identikits were released last month, Western Cape police said they had received an "incredible" response from the public.

At the time, police said they were looking for four suspects who reportedly drove away from the scene in an older model white BMW.

Seven employees of the gay massage parlour, a client, and the owner were massacred. They were found tied up and shot in the back of the head with a 9mm pistol in the early hours of January 20.

Most of them also had their throats slit with a carpet knife.

The sole survivor of the attack, believed to be a man in his 20s, is recovering under police guard in Groote Schuur Hospital.