The deportations happened shortly before Switzerland's August 26 decision to halt the forced returns of rejected Sri Lankan asylum seekers, amid growing human rights concerns since the separatists' defeat in 2009.
The Swiss Federal Office for Migration said the two men, whom it did not identify, were taken into custody at the airport in the Sri Lankan capital Colombo.
In a statement, it said they were accused of "taking part in activities in the service of the LTTE," or Tamil Tigers.
"The Sri Lankan authorities have agreed in principle to allow Swiss representatives to visit the two men in custody," it added.
The men's asylum claims were rejected in 2011, and they were sent home after a court upheld their deportation orders.
"In order to be able to check carefully whether a person is exposed to danger in their home country, the Swiss asylum authorities rely on asylum seekers to declare all the relevant facts relating to their situation," the office said.
"There may also have been shortcomings in the work processing the asylum applications of the two detainees," it added, saying that it had asked the UN high commissioner for refugees to review their cases.
Switzerland is home to a large community of Sri Lankan Tamils, who first arrived in the Alpine country during their homeland's civil war. Some of its members have in the past been accused of raising funds for the rebels.
The UN estimates that up to 100,000 people died during Sri Lanka's conflict between 1972 and 2009, when the Tamil Tigers made suicide bombings their hallmark.
UN human rights chief Navi Pillay is trading blame with Sri Lanka over its alleged failure to probe war crimes -- campaigners say 40,000 civilians were killed in the final offensive against the rebels -- or halt ongoing rights abuses.
Sri Lanka has rejected the charges, maintaining that its troops did not kill a single civilian and that it is making great strides in its reconciliation process.
AFP
