The Israeli foreign ministry confirmed that a Norweigan doctor with a long record as an anti-Israel activist has been banned from entering Israel, but denied reports he was also being blocked from visiting Gaza. "He has been banned from entering Israel," foreign ministry spokesman Paul Hirschson told AFP, but he added that contrary to previous reports the ban was not necessarily permanent. Hirschson denied the ban was a punitive measure, saying it was "exclusively a result of security considerations." He did not elaborate. "The decision is exclusively a result of a security consideration. It is not a punishment, and therefore it has no time frame," he said. "It is not 'forever' as some have implied, but for as long as the security considerations which have led to it remain the same." Gilbert told Norwegian media he had found out about the ban after working at Shifa Hospital in Gaza over the summer, which Hamas used as a hideout for its top terrorist leaders during Operation Protective Edge. When he tried to return to Gaza in October to "follow up on patients" and take part in several project at the hospital, he reports being stopped. "I was asked by the Norwegian authorities to go down to continue working in Gaza. When we arrived at the Erez Crossing, I was told by Israeli soldiers that I could not go into Gaza. I had to turn back to Norway," Gilbert told the Norweigan-language paper NRK . Reportedly the Norweigan Embassy in Tel Aviv is seeking recourse in Gilbert's case, and he says he is considering work around plans, such as ntering Gaza from Egypt. However Egypt has closed its Rafah border crossing since a deadly suicide bombing in northern Sinai on October 24, leaving Israel's Erez Crossing as the only entry point into Gaza - and effectively preventing Gilbert from entering the Islamist-ruled enclave. Gilbert gained notoriety in 2009 when he openly voiced his support for Al Qaeda's 9/11 terrorist attack during an interview with Norway's Dagbladet . More recently, he was one of the co-editors of an anti-Israel "Open Letter for the People in Gaza" published in July in the medical journal The Lancet . The letter raised an outcry, particularly after two of the primary authors - Dr. Swee Ang Chai and Dr. Paola Manduca - were discovered to have promoted an anti-Semitic video by white supremacist David Duke.