Judy Murray called for major changes to be made to the Fed Cup after resigning from her role as Great Britain captain.

Murray was appointed to lead Britain's team in the women's equivalent of the Davis Cup in 2011 but was unable to achieve her goal of promotion to the World Group.

The 56-year-old said she was stepping aside to focus on her grass-roots programmes, where her real passion lies, and to spend more time with her family following the birth of granddaughter Sophia.

Murray said: "I'm stepping down as Aegon GB Fed Cup captain to spend more time with my family and to focus on my grass-roots programmes, 'Tennis on the Road' and 'Miss-Hits'.

"I've loved the challenge of leading the team over the past five years, raising the profile of the event, our players and women's tennis in this country."

Getting out of the Europe/Africa Zone in Fed Cup, where Britain have been stuck since the early 1990s, is notoriously difficult.

Murray guided her team to the World Group II play-offs in her first two years in charge but Britain were beaten first by Sweden and then Argentina.

That left them back where they started and for the last three years their campaign has begun and ended with the round-robin zonal competition in February.

With first Elena Baltacha and Anne Keothavong and then Heather Watson, Laura Robson and Johanna Konta to call on, Murray has not been short of talent, but withdrawals have been a frustration.

Illness and injury have hampered Watson and Robson over the last three seasons while Konta pulled out of last month's competition through illness after reaching the semi-finals of the Australian Open.

Britain won two matches but lost to Belgium with a place in the World Group II play-offs at stake.

Murray had hoped to earn Britain a home tie, giving her players the chance to experience something of the excitement that carried the Davis Cup team, led by her sons Andy and Jamie, to the trophy last year.

Her statement continued: "It's a big regret for me that we didn't make it to the World Group, but what we have now is a pool of players capable of competing at that level. We just need them all to be available and fit to play at the same time.

"The Fed Cup format is in desperate need of a revamp. Team competition engages players and fans much more than individual events. It's crucial we use this global competition as a means of attracting and retaining girls in competitive tennis at every level.

"That requires more countries to have the opportunity of playing home and away ties so we can showcase our sport.

"The Fed Cup should be leading the way in promoting and showcasing competitive women's team tennis at all levels and in all countries. Things have got to change.

"Everyone can see the buzz created around the home ties and team tennis at all stages of the Davis Cup. Fed Cup should be afforded a similar format."

Watson, who took on Murray as a temporary coach in January, said on Twitter: "It won't be the same without you gorgeous @judmoo."

Murray's profile certainly created extra interest in Fed Cup and her resignation is a blow for the Lawn Tennis Association.

The process of appointing a successor will now begin, although, with the next fixtures not until February 2017, there is no hurry.

LTA chief executive Michael Downey said: "British Tennis and our players have been fortunate in having a captain possessing Judy's unique tennis knowledge, passion for the game, and sense of fun steering our Fed Cup campaign for the last five years.

"No doubt she has left an indelible mark on all the players she has worked with on the team, the support staff and inspiring other GB female coaches along that journey.

"On behalf of British Tennis, I would also like to personally thank Judy for her commitment.

"We will begin an open recruitment process shortly and aim to announce a successor well before the end of the year."

The ITF responded to Murray's statement, saying: "Judy Murray has been a dedicated ‪Fed Cup by BNP Paribas‬ captain for Great Britain and we are sorry to see her step down. Her energy and commitment to her team were very much in the spirit of Fed Cup and she will be missed.

"Like many captains and nations, Judy would like to see the Fed Cup format changed to a 16-team World Group which would allow more movement of teams from Zonal Groups into the World Group. This is a view shared by ITF President David Haggerty who with the board are looking at reforms to Fed Cup as well as Davis Cup. The ITF Board has an upcoming meeting where various reforms will be discussed, some of which may be brought to the ITF Annual General Meeting in June for consideration of approval."