A reformist politician in Iran said on Saturday that authorities have blocked two Web sites promoting the presidential bid of challenger Mohammed Khatami. The former president declared this month that he would challenge President Mahmoud Ahmadinejad in the June 12 election. That set the stage for a major political showdown in coming months between the popular reformist and the country's ruling hard-liners. Khatami made dialogue with the West a centerpiece of his eight years in office. Prominent reformist Majid Ansari said Saturday that by blocking the sites, authorities were seeking to increase pressure on reformists before the election.