R&B singer Kelis is desperately seeking financial support from estranged husband NAS to cover the mounting expenses of their unborn child - insisting she has "run out of money".

The former supercouple shocked the hip-hop world when the Milkshake hitmaker filed divorce papers on 30 April, citing "irreconcilable differences" for the break-up after almost six years of marriage.

The pair is expecting its first child together, and the battle for child support and custody of the unborn baby is escalating, since Nas urged a judge to deny his ex's request for spousal support and legal costs last month.

But Kelis is refusing to back down, and has filed legal papers for spousal support, child support, all pregnancy-related expenses and one-half of all medical expenses after the child is born, reports TMZ.com.

She has also reportedly asked for $3,500 for the baby nurse after the child's birth, and $20,000 for strollers, cribs and other baby supplies.

She claims: "I have run out of money... My survival is based on (Nas') will at this time. If he does not want to pay for an expense, it does not get paid."

The star is due to give birth on 21 July. The baby boy will be Kelis' first child and rapper Nas' second. The I Can MC also has a teenage daughter from a previous relationship.