It's  being billed as the bloodiest battle in showbiz, as Kerry Katona and ex-husband Brian McFadden's fight for custody of their two children becomes increasingly bitter.

Katona and McFadden, who were married for two years but split in 2004, have two daughters Molly, six, and Lilly-Sue, five.

In recent months the former Boyzone has upped his campaign against Katona, 27, first branding her "disgusting" and "an embarrassment".

Happy Days: Kerry Katona and Brian McFadden in happier times, the couple had two daughters but split in 2004 after a two year marriage

Katona with her new hubby Mark Croft during the pregnancy of the couple's first child

He has said to be unhappy with the way the children are being brought up and is alleged by Heat magazine to have told a friend: "They have got really terrible northern, Manchester accents. They're really common because of where they live and who they live with."

Last month McFadden, also 28, who lives with partner Delta Goodrem in Australia, told a Sunday newspaper:

"Kerry is a disgusting human being. She manipulates people and plays the sympathy card for every stupid mistake she makes. Me and my family have been put through hell by her stupid games.

She uses my two girls as a weapon in her childish games. She is an embarrassment to me, my family and my children."

The Atomic Kitten singer has now hit back. Her friend Sophie told the magazine: "Kerry is not scares, she's upset and disappointed because Brian seems to making a habit of attacking her and it is all one-way traffic.

The only way that Brian seems to be able to attract any sort of media interest or publicity is by attacking Kerry."

It is understood that McFadden is becoming increasingly frustrated by the custody situation, and has admitted he is worried his daughters will see Kerry's wild lifestyle, recently documented in her reality show Crazy in Love, as normal.

His mother Mairead has defended her son's public criticism of his former partner and is determined he will get custody of the girls.

However Katona's camp have dismissed this. Sophie said: "Social Services have been to see Kerry before and have told her they are happy and not to worry.

It's all nonsense. Kerry wants him to see the girls, so this whole thing doesn't make a lot of sense."

Unhappy: Kerry Katona has a face like thunder as she leaves her Warrington home today