Cosatu's deputy president Zingiswa Losi and deputy international organiser Zanele Matebula were arrested in Swaziland on Wednesday, it said.
Congress of SA Trade Unions' (Cosatu) spokesman Patrick Craven said he heard the two were being deported, but did not have further details.
Earlier, French news agency AFP reported that Losi and Matebula were arrested in the southern Swazi town of Sitheki during a pro-democracy march.
Police fired teargas and rubber bullets to break up the protest.
The head of the Swaziland National Association of Teachers, Sibongile Mazibuko, told AFP that when the Cosatu representatives got up to speak, police tried to remove them.
"The crowd tried to protect them. There were gunshots, teargas. I think they are being taken back to their country," said Mazibuko.
On Tuesday, Cosatu said it had sent a delegation to Swaziland to take part in a week of protests.
International relations secretary Bongani Masuku said 45 people from Cosatu, its affiliates and civil society organisations had joined the protests.
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