Israel has closed border crossings into the Gaza Strip, after militants fired a rocket from the territory, threatening a shaky four-month cease-fire.

Israeli police say the rocket caused no injuries or damage when it struck southern Israel Tuesday. It was the first rocket fired from Gaza toward Israel in more than a month.

Israel and the Hamas movement, which controls Gaza, reached a truce in June. Hamas agreed to stop firing rockets into Israel, and Israeli authorities agreed to gradually lift the blockade on Gaza.

Israel has virtually sealed off Gaza since Hamas seized control of the territory last year. It has allowed in only limited amounts of humanitarian aid, although more has been permitted since the cease-fire went into effect.

Israel controls all the territory's border crossings except one, on the Egyptian border, and Egyptian authorities have largely kept that post closed as well.

Hamas won a majority in the 2006 parliamentary elections but a Hamas-led government was crippled by Western financial sanctions and lack of recognition because of Hamas' refusal to accept Israel.

Hamas and the more moderate Fatah faction then briefly formed a unity government, but that fell apart in factional fighting and Hamas seized control of Gaza in June 2007. Fatah has since controlled the West Bank and the Palestinian Authority, while Hamas remains in control of Gaza.

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