Kerry claims that Mark has not been in touch with her or their two children, aged five and six, for over a year, only making contact in February last year when he sent her a text to wish son Max a happy birthday.
However, in his legal papers Croft claims that he has tried to get in touch with the 32-year-old singer.
A former notice summoning Kerry to appear at Warrington county court in Cheshire arrived to her family home on Friday.
A friend of the ex-Atomic Kitten star said: ‘If Mark wanted to see the children he could have called Kerry, her mum Sue or her manager. She’s upset he felt the need to do things so formally.
She doesn’t have any problem with Mark seeing the kids. She’s always wanted him to be more involved, but she does worry he’s going to mess them around.
He could have called Max on his birthday. He couldn’t even read the text messages because he’s too young.’
The same friend has accused Kerry’s ex-husband of trying to gain publicity during a financially difficult time for Kerry and her family.
She added: ‘Kerry’s trying so hard to be strong while looking for a smaller home and new schools for the kids.
It’s an unsettling time for all of them, so for him to stoke the fire right now, having never given a damn before, is absolutely disgusting. Rather than spend money on the kids or their birthdays, he’s spent it going straight to a solicitor. It’s come as a bolt from the blue to Kerry.
It just looks like he’s trying to wriggle back into the limelight.’
Croft previously complained that he couldn’t afford to see his children while Kerry lived in Surrey, but after moving back north earlier this year she now lives just 10 miles away form Croft’s home in Warrington.
Kerry married Mark in 2007 but the couple split three years later.