NEW DELHI, Feb. 24 (Xinhua) -- Indian authorities have seized over 10,000 imported luxury watches belonging to disgraced billionaire jeweller Nirav Modi and his firms in connection with the country's biggest-ever bank fraud of 1.8 billion U.S. dollars, an enforcement official said Saturday.

"All the luxury watches were meant for sale through Modi's jewellery stores across India. Earlier, we froze shares and mutual funds of Modi and also seized his nine luxury cars include Porsche Panamera, Rolls Royce Ghost and Mercedes Benz," said the official.

Modi is said to have defrauded Punjab National Bank, India's second largest state-run bank, of 1.8 billion U.S. dollars, though he said that he owed the bank only 775 million U.S. dollars, in a letter sent to the bank's management.

Investigators have so far arrested 12 people, including high-ranking bank officials, for their alleged involvement in the fraud.

But the jeweller, the mastermind of the massive fraud, is said to have fled the country and was reportedly last seen in New York after his appearance at the World Economic Forum in Davos as a part of an Indian delegation.

Though India has not yet charged Modi and only suspended his passport as well as his uncle and business partner Mehul Choksi's for four weeks, threatening to take strict legal action in case of his failure to respond to the government's notice.