Egypt is interrogating around 50 people for allegedly belonging to the Lebanese Shi'ite Hizbullah organization and for funding and supporting Hamas in the Gaza Strip, "knowledgeable legal sources" told Al-Jazeera. The state security prosecution started probing Egyptian, Lebanese and Palestinian suspects this week, the report said. They were arrested over the past six months and have subsequently hired an Egyptian lawyer to defend their case. The report said the investigation began last Saturday, and that the lawyer has not been allowed to meet the suspects. When the border between Egypt and the Gaza Strip is closed, Palestinians enter the Sinai Peninsula via underground tunnels. It is believed that the Sinai is teeming with illegal Palestinian residents who have fled Gaza. Egypt is trying to show the West, and especially the United States, that it is serious in its efforts to clamp down on terror groups and bring about stability in the region. Cairo is a recipient of considerable aid from Washington. Cairo is also concerned that if Hamas gains more power across the border, it will embolden its own Muslim Brotherhood, the largest opposition group in Egypt. The brotherhood has been banned since 1954 but it is tolerated to some extent and its popularity poses a threat to the ruling National Democratic Party. Both Hizbullah and Hamas are supported by Iran, which has a longstanding dispute with Egypt. Iran's controversial nuclear program is a concern for Egypt and other Sunni states in the region, which fear the prospect of a nuclear Iran. There have been frequent reports over the past year of Egyptian security forces finding weapons caches that were believed to be intended for smuggling into Gaza and into the hands of Hamas.