Britney and Kevin reunite for sons` special day

New York: Pop star Britney Spears and her ex-husband Kevin Federline came together for their sons` pre-school graduation.

Spears, who formally separated from Federline in 2007, was accompanied by her parents.

Federline arrived separately at their sons` school, but the two met up briefly.

Their children - Preston, 4, and Jayden, 3, - were later treated to Happy Meals at the McDonald`s after the ceremony, says quoting a source close to the family.

Spears, 28, "was very excited about her boys` graduation and she dressed them up for the festive occasion", added the source.

The duo had tied the knot in 2004, but split in late 2006 before finalising their divorce a year later.

A custody settlement in 2008 gave Federline, 32, sole custody of the children while Spears was allowed several weekly visits.