IFSL operates 360,000 vehicles and employs 1,400 people.
An IFSL spokesman said: 'IFSL's scale enabled it to secure a contract with National delivering true economies and improvements in customer service proposition. Daily rental services have become a critical part of IFSL's full service leasing offering and it will work closely with National to provide an efficient, consistent and competitive service across the whole IFSL network.'
As part of the deal, National has also been appointed as preferred supplier to UK-based HSBC Vehicle Finance, a founding member of IFSL.
Ron Santiago, vice-president international sales & marketing for National Car Rental, said: 'We are very pleased to play a crucial role in the on-going success of IFSL. This really demonstrates how National is becoming a force to be reckoned with on an international scale, building on our expertise in the fleet and corporate sector to create partnerships such as this, which deliver a quality and added-value service to customers throughout our international network.'
Steve Simpson, IFSL's general manager, said National was chosen for its presence in a large number of countries and competitive rates, adding: 'But, perhaps most importantly, we selected National for its innovative ideas for developing IFSL's service proposition.'