Former Russian oil tycoon Mikhail Khodorkovsky traveled to Switzerland on Sunday, ostensibly on a family errand to bring his two sons back to school. But Khodorkovsky told Swiss television in an interview that he planned to keep campaigning for the release of political prisoners in Russia. The businessman - who spent more than a decade in prison on what many in the West considered trumped-up charges - was pardoned last month by his longtime foe, Russian President Vladimir Putin. There has been speculation that Khodorkovsky might seek to make a permanent home in Switzerland after telling reporters that he won't return to Russia for the time being. The 50-year-old has long business ties to Switzerland from his time as head of the now-defunct Yukos oil company. "The trip to Switzerland is for family reasons," spokesman Christian Hanne said in a statement. Mr. Khodorkovsky hasn't made any plans concerning the question of whether he would like to permanently live in Switzerland. Khodorkovsky traveled by train Sunday from Berlin, where he had been since his Dec. 20 release, to Basel, Switzerland. The trip became possible after Switzerland gave him a three-month visa that allows him to travel freely within the 26-nation Schengen area, which includes Switzerland and most of the European Union but not Britain. In an interview with Swiss television station SRF recorded during the train journey, Khodorkovsky said he felt a responsibility to help others in Russia who remain imprisoned for their political views. "I want to do as much as possible to help secure the release of other political prisoners," he said. Khodorkovsky has indicated that he retains some of the vast wealth that once made him Russia's richest man. When he was prosecuted in Russia for tax evasion and money-laundering, Russian officials sought to seize about $5 billion linked to Yukos that had been deposited in Switzerland. But Swiss authorities refused to hand over the money, concluding that his prosecution was politically motivated. "Mikhail Khodorkovsky is grateful for the clear position the Swiss authorities took during his many years in unjustified imprisonment," Hanne said. The Swiss legal authorities contributed significantly to making the political nature of his prosecution apparent. It's not clear how much of the money in Switzerland remains and whether Khodorkovsky has direct access to it.