Britain has already contributed more than 60 million euros and "there will be around an extra 20 million euros (USD 15 million)" Harlem Desir told RFI radio, with the money used to boost "security of the access zone to the tunnel... And fighting trafficking networks".
The announcement came hours ahead of a summit between French President Francois Hollande and British Prime Minister David Cameron in the northern city of Amiens, where the Calais crisis will be top of the agenda.
The camp, built on a former toxic waste dump, is a magnet for people hoping to reach Britain and many have refused to leave, although there has been no repeat of the violent clashes that erupted on Monday.
French Economy Minister Emmanuel Macron told the Financial Times yesterday that if Britain left the European Union following a referendum in June, France would cease keeping the migrants in Calais.