UK Stocks-Factors to watch on Jan 17

Jan 17 (Reuters) - Britain's FTSE 100 index is seen opening down 21 points at 7,735.3 on Wednesday, according to financial bookmakers. * RIO TINTO: Rio Tinto Plc on Tuesday said a U.S. regulator's lawsuit accusing the big Anglo-Australian mining company of fraud for overstating the value of Mozambique coal assets it had bought in 2011 should be dismissed. * INFORMA-UBM: Britain's Informa is in talks about a deal to buy events organiser UBM for more than 3 billion pounds ($4.