SINGAPORE, Aug 10 (Reuters) - Singapore's benchmark Straits Times Index fell 3.1 percent at the open of trading on Friday, tracking Wall Street's tumble.

Banks led losses, with DBS Group Holdings down 4.6 percent. United Overseas Bank fell 3.3 percent and Oversea-Chinese Banking Corp. slipped 4 percent.

U.S. stocks tumbled on Thursday, with the Dow down nearly 3 percent, after a French bank froze three funds that invested in U.S. subprime mortgages, prompting central banks to take steps to calm investors.