Staying friends with an ex may be the civilised thing to do - but it could spell the death knell for a new relationship.

Those who keep in touch with a former partner have less commitment to their current one, a study warns.

And a significant number may also be looking for a "back-up plan".

Nearly half of us still keep in touch with a former spouse or partner even after moving on to a new romance, a study by psychologists at South Florida University found. While most claim it is for friendship's sake, the degree of closeness should ring warning bells according to study leader Professor Lindsey Rodriguez.


"Those who communicated with exes reported lower levels of commitment to their current partner, poorer adjustment to the break-up, and higher levels of romantic emotions toward their former partner," she said.

In the study of 429 people - almost three-quarters of them women - more than 40 per cent said they still communicated with their most recent ex - 13 per cent doing so several times per week.

The study in the journal Personal Relationships found those least likely to talk were either married or engaged.

But when other "desirable alternatives" to the current relationship are available, "commitment may decrease, particularly given romantic - back-up - motivations with the former romantic partner", warned Prof Rodriguez.