Libyan state TV says Misurata port has been rendered "non-functional". Nato has accused Gaddafi's forces of mining the harbour to block aid ships.
Friday's clashes was the first time government troops had crossed the border and entered a Tunisian town.
Inside Libya, NATO air strikes hit Gaddafi's troops attacking rebel-hit Zintan. The claim did nothing to stop loyalists from firing 20 rockets into the city.

Thousands of rebels and civilians gather for Friday prayers in central Ajdabiya [Reuters]