Clamping system for connecting two tubes having protruding clamping surfaces. The system comprises a collar having a strip able to cooperate with the clamping surfaces. The strip has a first and a second flank between which an inner recess able to receive the clamping surfaces is delimited. The system has at least one retaining clip having a cross-member which extends across the inner recess, a first and a second wing which extend radially outwardly relative to the cross-member by covering the flanks and a first and a second retaining configuration each having at least one retaining lug. The cross-member is able to be deformed to penetrate into the inner recess.