Mr Seniora said his government knew nothing of Hezbollah's border raid that captured two Israeli soldiers and killed more than eight people last Wednesday.
He appealed to Lebanon's friends around the world to rush to its aid.
The Arab League has called on the United Nations to act, declaring that the Middle East peace process is dead.
The conflict also dominated discussions at the G8 summit in Russia. Russian President Vladimir Putin said he believed Israel was pursuing wider goals in its military campaign than the return of abducted soldiers. He did not elaborate.
US President George W. Bush accused Hezbollah of igniting the crisis.
As tensions rose in the Middle East, Palestinian witnesses claimed at least 40 Israeli army tanks and armoured vehicles had rolled into the northern Gaza Strip.
Palestinian sources said the Israeli army vehicles had seized locations in northern and eastern Beit Hanoun.