LONDON (Reuters) - British military intelligence said on Sunday that Russian forces were targeting populated areas in Ukraine but that the strength of resistance was slowing the Russian advance.

       "The scale and strength of Ukrainian resistance continue to surprise Russia," British military intelligence said in an update. Russia "has responded by targeting populated areas in multiple locations, including Kharkiv, Chernihiv and Mariupol."

       "Russia has previously used similar tactics in Chechnya in 1999 and Syria in 2016, employing both air and ground-based munitions," British military intelligence said.

       Russia has repeatedly denied that it is targeting civilian areas.

       (Reporting by Guy Faulconbridge; Editing by Kim Coghill)