Boris Johnson waded in to the row between steel tycoon Lakshmi Mittal and the French government as he urged Indian businessmen to set up in the United Kingdom.
He called French industry minister Arnaud Montebourg, who accused Mr Mittal of leaving the country after he announced the closure of two blast furnaces in the north-eastern region of Florange, an "eccentric", telling an audience of businessmen in Delhi they should avoid "persecution" in Paris and base their European operations in London.
The row erupted after the socialist minister Mr Montebourg said ArcelorMittal - the world's biggest steelmaker owned by Mr Mittal - had shown a lack of respect to France.
"We don't want Mittal in France anymore because they haven't respected France," Mr Montebourg was quoted as saying in the business newspaper Les Echos. The trouble, he said, "isn't the furnaces in Florange, it's Mittal".