LONDON, Jan 23 (Reuters) – North Sea Forties crude differentials rose on Thursday, supported by increased buying interest. PLATTS WINDOW * Forties: Mercuria sold to Exxon a CIF Rotterdam cargo for Feb. 4-8 at dated Brent plus 90 cents, up 30 cents from a similar cost, insurance and freight (CIF) Rotterdam basis deal on Wednesday. * Forties: Glencore bid for a Feb. 9-13 cargo at dated Brent plus 10 cents and a Feb. 19-21 cargo at dated Brent plus 25 cents. (Reporting by Alex Lawler; Editing by Elaine Hardcastle)