Chiliboy Ralepelle and Bjorn Basson have both been sent home
South Africa duo Chiliboy Ralepelle and Bjorn Basson have been suspended and sent home after failing drugs tests.
Hooker Ralepelle and winger Basson tested positive for a banned stimulant following the Springboks' 23-21 win over Ireland in Dublin on 6 November.
The South African Rugby Union was told of the positive tests late on Sunday.
Coach Peter de Villiers fears the whole squad may have taken the banned substance and the team's energy drinks have been sent for testing.
He told South African broadcaster Supersport: "We don't want to put the players at risk. If there is something that we are taking as a squad that might have caused this then we must find that out now."
Both players have tested positive for methylhexaneamine, a "non-specified stimulant" on the prohibited substances list of the
World Anti-Doping Agency
Springboks doctor Craig Roberts said that the players had been taking medication for flu symptoms.
The pair both featured in Saturday's 29-25 victory against Wales, Ralepelle coming on as a late substitute while Basson started.
Basson was due to fly back on Monday in any event as he injured his ankle in the win at the Millennium Stadium and had been ruled out of the rest of the tour.
The 23-year-old winger, who set the record for the most tries scored in a season in South Africa's domestic Currie Cup competition this year, won the third of his four caps in the 23-21 win against Ireland.
He started the game in Dublin, while Ralepelle was an unused substitute.
Ralepelle, a 24-year-old hooker who has won 18 caps, was the first black player to captain South Africa when he led them out against a World XV in Leicester in 2006.
Methylhexaneamine is scheduled to be reclassified as a "specified stimulant" from 1 January 2011, which means it will join the list of drugs that are more susceptible to being taken by mistake.
That means they can be punished less severely if athletes can prove they did not take the drug in order to improve performance.
The players have the right to request that their 'B' sample be tested, while the penalties they potentially face range from a warning to a two-year ban.
The Australian Sports Anti-Doping Authority said in October that nine unidentified Australian athletes had tested positive for methylhexaneamine.
At the 2010 Commonwealth Games in New Delhi in October, two Nigerian runners - Osayomi Oludamola and Samuel Okon - also tested positive for the stimulant.
South Africa face Scotland on Saturday before tackling England at Twickenham on 27 November, before their tour closes with a game against the Barbarians on 4 December.
Highlights - Ireland 21-23 South Africa