Breaking up is hard to do and staying friends on social networking sites such as Facebook may make it harder, British researchers say.

Tara C. Marshall of Brunel University in Uxbridge, England, said previous research found continuing offline contact with an ex-romantic partner following a breakup may disrupt emotional recovery. The present study examined whether continuing online contact with an ex-partner through remaining Facebook friends and/or engaging in surveillance of the ex-partner's Facebook page inhibited post-breakup adjustment and growth.

More than 900 million people worldwide are active users of the social networking site Facebook, and it is estimated that as many as one-third report using Facebook to check on the activities of former romantic partners, Marshall said.

The researchers collected data from 464 participants to evaluate their Facebook usage and their emotional recovery and personal adjustment following the breakup of a romantic relationship.

The study published found Facebook surveillance was associated with greater current distress over the breakup, more negative feelings, sexual desire, longing for the ex-partner and lower personal growth.

The findings were published in the journal Cyberpsychology, Behavior and Social Networking.