NEW : Another humanitarian group also supplied photos of casualties to CNN . Government shelling also wounds 1,200 , aid worker says . Comment: Sri Lanka denies rebel claims that troops indiscriminately shelled no-fire zone . Government says troops advance into rebel-held areas .
NEW : Government shelling also wounds 1,200 , aid worker says . Comment: Sri Lanka denies rebel claims that troops indiscriminately shelled no-fire zone . Government says troops advance into rebel-held areas .