FORT COLLINS (Reuters) - The parents of a Colorado boy whose apparent brush with death in a helium balloon transfixed millions pleaded guilty on Friday to staging a publicity-seeking hoax and will be sentenced next month.

Richard and Mayumi Heene pleaded guilty to a felony and a misdemeanor and will be sentenced on December 23.

The case has sparked outrage over the amount of money spent on a rescue attempt for the six-year-old child, dubbed "balloon boy," after live television images of the saucer-like homemade balloon soaring through the sky gripped the public.

The judge at Friday's hearing told the Heenes they may have to pay to various government agencies some of the cost of the rescue attempt, which had National Guard helicopters chasing the balloon.

"There are financial consequences that could be significant," District Judge Stephen Schapanski said.

The boy's parents agreed to a plea deal under threat that prosecutors would seek to deport the mother, a Japanese citizen, if she were convicted of more serious charges.

Richard Heene, 48, pleaded guilty to attempting to influence a public servant and Mayumi Heene, 45, pleaded guilty to a misdemeanor charge of false reporting to authorities.

The Heenes drew worldwide attention last month when they said their son had unwittingly sailed away in the balloon. But it landed empty, the boy turned up at home and the mother admitted it was a stunt aimed at making the family marketable for a reality TV show.

Defense attorney David Lane said this week prosecutors had agreed to recommend sentences of probation with the possibility of up to 60 days in jail for the wife and 90 days for the husband.