LONDON (Reuters) - The British government made several assurances to Japanese carmaker Nissan <7201.T> before last week's announcement it would build two new models in Britain, business minister Greg Clark said on Monday.

The decision to build the models at Britain's largest car plant, rather than elsewhere in Europe, was won with what a source described as a government promise of extra support to counter any loss of competitiveness caused by Britain leaving the EU.

Clark said several assurances had been important in securing Nissan's investment, including efforts to ensure more of the automotive supply chain is located in Britain, and pushing for free trade with the EU in upcoming Brexit negotiations.

"In our negotiations to leave the EU, we will emphasize the very strong common ground that there is, especially in the automotive sector, between ourselves and other EU member states, in ensuring that trade between us can be free and unencumbered by impediments," he told parliament.

(Reporting by Wililam James and Kylie MacLellan; editing by Stephen Addison)