COLOMBO, April 24 (Reuters) - Tamil Tiger aircraft bombed a Sri Lankan military air base in the north of the country early on Tuesday, the second such strike by the rebel group. "Tamil Tigers air wing attacked Palaali airstrip and military storage," rebel military spokesman Ilanthirayan said by telephone. "Our aircraft returned safely." He said the extent of the damage was unknown, but the pro-Tiger Web site Tamilnet reported the attack inflicted "heavy damage" to a military garrison. A government military spokesman could not be reached for a comment.