Prime Minister Ehud Olmert is visiting the site of Israel's main nuclear reactor, an Israeli official said Tuesday. The official did not say what the purpose of Olmert's visit was, however Army Radio reported that the prime minister was given a guided tour of the facility. But the unusual visit to the site in the southern town of Dimona on Tuesday takes place against the backdrop of broader tensions between Israel and Iran over Teheran's nuclear program. Israel disputes Iran's contention that it doesn't plan to build bombs. US defense officials have suggested Israel is preparing to attack Iran. Israel favors tough sanctions to pressure Iran to scale back its nuclear ambitions, but Olmert pointedly has not ruled out an attack.