JERUSALEM — Egypt’s new ambassador to Israel formally assumed his post Wednesday, saying his country’s Islamist government remains committed to peace with the Jewish state.

Israel and Egypt signed a peace agreement in 1979 that has since been the bedrock of relations between the countries, but ties have grown tense since Egypt’s longtime president, Hosni Mubarak, a steadfast supporter of the treaty, was ousted in a popular uprising last year and Mohammed Morsi, an Islamist, was elected his successor in June.