Britain and France are to sign an agreement to combat the Calais migrant crisis.
The deal will focus on strengthening security at the port where thousands of migrants are trying to get to Britain via boats and the Eurotunnel.
Home Secretary Theresa May will travel to Calais on Thursday to sign the agreement with her counterpart Bernard Cazeneuve.
It will contain measures to deal with human traffickers who facilitate migrants' journeys.
Commitments to boosting humanitarian support for the most vulnerable migrants will also be written in to the pledge.
Immigration Minister James Brokenshire said: "Illegal working cheats the taxpayer, undercuts honest employers and means legitimate job seekers are denied employment opportunities.
"That is why since 2010 we have taken a wide range of measures to make it systematically harder for people to enter illegally, work and remain in the UK.
"We have made it much tougher for illegal immigrants to access benefits, healthcare, bank accounts and driving licences, and doubled the penalty for employers who give jobs to those with no right to be here – to £20,000 for each individual found employed.
"The new Immigration Bill will also introduce an offence of illegal working, making it clear to migrants who have no right to here that working illegally in the UK is a crime, with consequences for their earnings."