TOKYO, May 25 (Reuters) - Japan's net external assets fell for a third straight year in 2017 as rises in gross overseas debt outpaced asset gains, though the country remained the biggest creditor nation for the 27th straight year, the Ministry of Finance (MOF) said on Friday.

The net value of assets held by the government, businesses and individuals stood at 328 trillion yen ($3 trillion) at the end of 2017 - down 2.3 percent from the year before and compared with 2014's record 363 trillion yen, the ministry said.