It is time for the men's and women's professional tennis bodies to merge, says former world number one Kim Clijsters, who wants a united front in the sport as the Women's Tennis Association (WTA) celebrates its 50-year anniversary.

The Belgian's remarks echo a sentiment long held by the great Billie Jean King, who pioneered the circuit half a century ago and will be on hand at Wimbledon this week to celebrate the WTA's decades of promoting equity for women in sport.

"Would I like to see it (ATP/WTA merger)? Yeah I think it would make the brand so much stronger," the four-time Grand Slam champion told Reuters referring to the men's Association of Tennis Professionals body.

"A lot of times to the outside world people automatically assume that it is one organisation. You know what I mean? Like people who don't know much about tennis, they say, 'Oh yea, ATP and WTA', but behind it there's one unit.' But that's, you know, far from that."

Clijsters, the honorary president of the International Tennis Hall of Fame (ITHF), said the impact of the WTA cannot be overstated, and counts meeting King and German great Steffi Graf among the biggest and most pivotal moments of her career.

The ITHF unveiled a video segment celebrating 50 years of the WTA this year called "TennisWorthy."

"There's so many people behind the scenes who are all kind of facing in the same direction and who want to see this trend of, you know, making (women's tennis) go upwards," said the 40-year-old Clijsters.

"As long as we all kind of have that mindset and it's not just one person who can make the difference, it's everybody together as a strong unit, group, I think that's the only way that we can go to get it to a place where combined events are putting the same amount of players - women as men - on center courts or late night matches."

King will return to the Millennium Gloucester Hotel, where the WTA was formed at a meeting of players, on Friday ahead of the start of the Wimbledon main draw next week. But she has long felt that the two sides – ATP and WTA – would be stronger together, an argument King reiterated after retired great Roger Federer resurfaced the idea three years ago.

"There's pros and cons to everything, right?" said Clijsters. "There have been many, many, many conversations about doing that. And you kind of always bump into a wall where, you know, not much happens and it stays with conversations. And of course, I would like to see, you know, there being one organisation."