Israel's defense ministry says it has again sealed its border with the Gaza Strip, in response to rocket fire.

Officials Tuesday said they decided to close the passage after Palestinian militants fired a rocket toward southern Israel on Monday. No casualties or damage were reported.

It is unclear if or when the borders will reopen.

Israel allowed several truckloads of humanitarian aid and other supplies into the area on Monday.

International concern about the shortage of basic goods in Gaza has mounted since Israel tightened its blockade of the Palestinian territory November 4.  Israeli officials say the action was prompted by an earlier surge in rocket and mortar attacks.

During a visit to Washington where he was meeting with Secretary of State Condoleezza Rice, Israeli Prime Minister Ehud Olmert defended the closure.  He told reporters Tuesday Israel did not want to take responsibility for the security of people passing through.

Journalists are also barred from entering Gaza.  Foreign media groups in Israel Monday appealed to the country's supreme court to overturn the ban, put in place earlier this month.

Israel routinely prevents its citizens, including journalists from entering Gaza, citing security concerns.  But until now, foreign reporters were allowed in.

The French News Agency quotes Mr. Olmert Tuesday saying "the situation in Gaza is much better than presented outside."

Some information for this report was provided by AP and Reuters.