SHANGHAI, July 6 (Reuters) - China's yuan hit a fresh 5-1/2 year low against the dollar in early trade on Wednesday, after the central bank set its official midpoint at its lowest level since November 2010.

The yuan hit 6.6940 per dollar in early trade against Tuesday's close of 6.6816, according to data from the China Foreign Exchange Trade System.

China's central bank on Wednesday set its yuan/dollar midpoint rate at 6.6857 prior to the market opening after the yuan had tumbled in late trade on Tuesday.

The dollar index rose over 0.5 percent against a basket of major currencies on Tuesday while the sterling sank to new depths on Brexit anxiety.

Wednesday's midpoint weakened 0.4 percent from the previous day's fix of 6.6594 per dollar, but wasn't far off the overnight spot yuan close at 6.6816, which had partially factored in the some of the dollar's strength.

(Reporting by Shanghai Newsroom; Editing by John Ruwitch and Kim Coghill)