London: You may want to consider putting your potential partner into the friend zone first as a new study suggests so.

According to the US psychologists, being friends in a relationship is the "most important factor" for satisfying sex life and longevity.

One of the authors, Laura VanderDrift, told The Independent that finding a partner who was "first and foremost a friend" was a good predictor of the long-term success of a relationship.

The study, carried out at Purdue University in Indiana, surveyed 184 people who had been in relationships for 16 months or more and asked them what they valued most about their relationship.

Dr VanderDrift noted that couples trying to improve their relationship could solve several problems at once simply by focusing on being friends and having more shared interests and "friendship-type experiences."

The study is published in the Journal of Social and Personal Relationships.