Kevin Federline and Britney Spears during their marriage. Picture: Bang Showbiz

Britney Spears' father will demand a copy of Kevin Federline's tax return before making any decisions about the dancer's request for increased child support.

The 'Toxic' singer currently pays Kevin Federline R236,000 a month for their sons Sean Preston, 12, and 11-year-old Jayden but the dancer recently requested the payments be increased as he didn't feel he was receiving enough money.

READ: Britney Spears' ex wants more child support

And after it was previously reported Jamie Spears - who, as co-conservator of his daughter's estate, has control of Britney's affairs - didn't feel the sum needed to be increased, it's now been revealed he wants to see a copy of Kevin's tax records to find out if he is working for a living.

According to TMZ, Kevin's legal team sent a letter earlier this week asking to see Britney's 2017 tax return, and Jamie is now planning to send an identical response in the next day or two.

Jamie is said to be refusing to pay Kevin - who also has children Kori, 15, and Kaleb, 13, with ex-fiancee Shar Jackson, and Jordan, six, and Peyton, three, with wife Victoria Prince - any more money until he is given a full account on how it will be spent as he believes the DJ is misusing his current payments to spend it on his other kids.

The development comes a week after Jamie received a letter from Kevin's lawyer asking for a talk, and when they got together, the legal representative claimed his client needed more money now the boys are getting older, in order to have the means to take care of them at the same level his ex-wife can.

And despite seeing her earnings rise since the original agreement was reached, largely due to her Las Vegas residency, Jamie insisted his 36-year-old daughter hasn't changed the way she looked after the children.

He also argued the 'Womanizer' hitmaker's success has nothing to do with the needs of the children and insisted his daughter wasn't responsible for taking care of Kevin and his other children.

Despite his requests for more money, the 39-year-old reality TV star and his lawyer didn't specify a figure and couldn't give an example of where the boys' needs weren't being met.

When the former couple got divorced in 2007, Britney paid her ex-husband $1.3 million, and as well as continued child support payments, he also received spousal support for several years.