The EU is looking to plug a big gap in  migration policy by boosting measures to have irregular migrants voluntarily returned to their countries under a strategy adopted on Tuesday.

Controversially, the European Commission's plan on return and reintegration puts the EU's border agency Frontex at its heart, despite multiple news reports and NGO allegations of rights abuses by its officers -- the bloc's first uniformed force.

EU Home Affairs Commissioner Ylva Johansson defended the agency's role from the cloud that lingers over it.

She told a media conference that, while "shortcomings" had been identified, an inquiry by Frontex's board had concluded last month "that the agency was not involved in this type of activity".

She added that the border agency was "very well placed" to help EU member states to encourage migrants with no right to stay to return to their countries of origin.