Rival Shiite militiamen battled for the fourth day Tuesday in Beirut's suburbs and southern Lebanon, defying a reported appeal by Iranian leader Ayatollah Ruhollah Khomeini to halt the warfare. The street fighting engulfed the impoverished, bullet-scarred suburbs south of Beirut and a cluster of villages in the district of Iklim Al Tofah, 28 miles south of the capital. Police said at least 24 people have been killed since New Year's Eve with 61 others wounded.