Guy Verhofstadt is currently discussing the Brexit process
The Belgian-born 64-year-old is addressing the European parliament's Commission for Constitutional Affairs as Brexit negotiations get underway.
He is set to outline the Brexit steering group's demands when it comes to EU nationals living in Britain.
Mr Verhofstadt said: "There needs to be reciprocity from the beginning when it comes to citizens' rights from beginning to end."
In a veiled threat to hold up the entire Brexit process, the staunch Europhile said the first thing Britain needed to do was work with the EU to finish a withdrawal agreement.
He said: "Only once this is done can we start to talk about the second phase, our relationship with Britain."
The Good Friday Agreement is also scheduled for discussion.
More to follow…