The government has installed a gate at the Ledra Street crossing to the north of the island, prompting criticism that it had turned it into a hard border.
The interior ministry had announced last Friday that it would be closing the crossing for 48 hours Tuesday to Thursday due to construction work.
On Thursday it transpired that the work concerned the installation of a gate and a prefabricated control post for officers policing the crossing.
Pro-reunification supporters took to the net to protest the action, suggesting the government had turned the crossing into a hard border.
Unite Cyprus Now tweeted: “Stop turning the Green Line into a hard, fenced border crossing through the heart of our capital!”