Forces loyal to the fugitive Libyan leader Moammar Gaddafi struck back Monday against the rebel fighters who had swept euphorically into the capital the night before, forcing them to retreat from several strategic locations and tempering hopes that the battle for Tripoli was all but over.

The dramatic appearance Monday night of Gaddafi’s son Saif al-Islam at the Rixos hotel, where the Tripoli-based press corps remains trapped, contradicted the rebels’ assertion the day before that they had captured him and cast into doubt their claim of controlling 80 percent of the capital.