Kevin Federline may have learned of Britney Spears's decision to divorce him from a text message he received while taping a show for Canadian television station MuchMusic.

Pop singer Britney Spears filed for divorce from her husband of two years on Tuesday, citing irreconcilable differences.

Kevin Federline and Britney Spears together in 2005. She has filed for divorce.
(Associated Press)

Legal papers in Los Angeles County Superior Court, however, listed the official day of separation as Monday, the day Federline was in Toronto filming an episode of Exposed for the music station.

A report from the network with video — available for viewing on YouTube — from the taping showed Federline taking a break from an interview to check his text messages, after which he abruptly took off his microphone and left for half an hour.

MuchMusic reported the former backup dancer turned rapper returned visibly upset and finished shooting the show.

Spears has asked for legal custody of their two children, one-year-old Sean Preston and two-month-old Jayden James, the papers say.

She has hired celebrity divorce lawyer Laura Wasser, who has represented stars such as Angelina Jolie, Nick Lachey and Kiefer Sutherland in divorce cases.

Spears and Federline married in September 2004 and are believed to have a prenuptial agreement.

The divorce petition states property rights are yet to be determined, but Spears is not requesting alimony.

Rapper Federline, 28, was in Toronto Monday promoting his new CD. In an interview at MuchMusic, he spoke of the support Spears has given him as he tried to launch his career as a singer.

"She's been with me the whole time," Federline said. "She's probably my No. 1 fan, you know what I'm saying?"

He also told MuchMusic he was a dedicated family man and devoted to his children.

"Being a father, it really, really grounds you," he said.

In an interview earlier this year, he said publicly that it is difficult living in the shadow of a pop princess.

Federline's lawyer, Mark Vincent Kaplan, issued a statement Tuesday declining comment on the divorce petition.

Spears, whose hits include Toxic and One More Time, made a surprise cameo on the Late Show with David Letterman on Monday evening, popping up behind host Letterman at one point.

The newly slender Spears was wearing a short black dress and had her hair cut in a blonde bob.

She told Letterman she was there to see Will Ferrell, a guest on the show, and went off-stage to meet the comedian.

In the past year, Spears has been more in the news for her parenting skills than her singing career and was criticized for allowing her son to ride in a car without a child seat.

In an interview in June, she told morning-show host Matt Lauer her marriage was wonderful, but said the constant attention from paparazzi was a strain on their family.