Britney Spears Celebrates her 25 Birthday (12/02/06)

Pregnancy, divorce and knickerless partying have made Britney Spears the most popular Yahoo search in the world for the fifth time in six years.

The star, who turned 25 at the weekend, gave birth to second son Jayden James in September, only to announce she was ditching his father, rapper Kevin Federline, two months later.

In recent weeks she has whipped up an internet storm after being photographed on nights out with hotel heiress Paris Hilton.

Spears' new best friend only managed fifth place in Yahoo's Buzz Index list of the most searched-for terms in 2006.

And Hollywood starlet Lindsay Lohan, who joined the blonde pair on several nights out, came in 10th.

Buzz spokeswoman Cathi Early said Spears would have won even without her recent late-night antics.

"It's not a surprise," she said.

"There is a definite fascination with her private life."

Prime Minister Tony Blair failed to make it on to to the list of top 10 politician searches, while US President George Bush headed up the chart.

California Governor Arnold Schwarzenegger came second and former US President Bill Clinton was third, followed by his wife Hillary.