Brazilian female rower Kissya Cataldo da Costa has also been expelled from the Olympics for failing a dope test for EPO prior to the start of the official Olympic period, a Brazilian rowing team official told Reuters.
The 18-year-old Palomeque is the fourth athlete to have been officially suspended, provisionally or permanently, from the Games since the start of the Olympic period on July 16.
Several other athletes have been confirmed as positive by their own federations.
Palomeque, scheduled to compete on Saturday, had provided a urine sample on 26 July in London that tested positive for testosterone of exogenous origin.
"Upon receipt of the results of the B sample analysis, a final decision will be pronounced by the Disciplinary Commission," the IOC said in a statement.
Should the second sample also come back positive, Palomeque faces a possible two-year suspension as a first-time offender.
Kissya, 30, tested positive for performance-boosting EPO in a pre-competition test carried out in Brazil on July 12 by the International Rowing Federation (FISA), the Brazilian Olympic Committee said.
Russian track cyclist Victoria Baranova, who has already been sent home, has been officially expelled following a July 24 positive test for testosterone in Belarus.
The 22-year-old Baranova, ranked two in the world in keirin, was a medal contender in London.
"I do not think this changes where we are at all," IOC spokesman Mark Adams told reporters when asked whether the latest positive tests were showing a wider use of banned substances at the Games than expected.
"Cheats are being caught and ejected," he said. "At this stage it is a pretty low number."
On Friday, Moroccan middle-distance runner Amine Laalou was thrown out of the Games after his team confirmed he had failed a doping test in July.
Uzbek gymnast Luiza Galiulina and Albanian weightlifter Hysen Pulaku have also been expelled by the IOC while St Kitts and Nevis sprinter Tameka Williams admitted to taking a banned substance and was told by her Olympic team to return home.
There were 20 proven cases of doping at the Beijing Games four years ago, including six horses, down from 26 cases in Athens in 2004.
- Sports & Recreation
- Addiction & Substance Abuse