European Commission President Ursula von der Leyen plans to travel to South America this week to sign the EU Mercosur trade deal.
The move is prompting fresh criticism, amid claims the agreement is being pushed ahead before a vote in the European Parliament.
A petition signed by more than 30 thousand people opposing Mercosur is being delivered, following a major protest in Athlone on Saturday.
Independent Ireland MEP Ciaran Mullooly says there are serious public health concerns about the deal: