Kenyan runner Robert Cheboror, the runner up in last year's Boston Marathon, has pulled out of Monday's race because of a visa problem.

A statement from the race's chief sponsor, John Hancock, said Saturday that Cheboror withdrew because of "difficulties obtaining official travel documents." No further details were given.

The Kenyan finished one minute, 12 seconds behind countryman Timothy Cherigat last year. Cheboror also won the Amsterdam marathon last year in two hours, six minutes, 23 seconds, the second fastest time of 2004.

Cheboror is the latest of several withdrawals from the race including Poland's Malgorzata Sobanska, who pulled out because of injury and Kenya's Paul Koech, who withdrew because of training problems.

The 109th Boston Marathon is scheduled for Monday and features 31 elite runners from 12 countries. The course covers 42-kilometers from Hopkinton, Massachusetts to downtown Boston.

Some information for this report provided by AP.