BRUSSELS—The European Union imposed wide-ranging economic sanctions on Belarus for the first time on Thursday, targeting its main export industries and access to finance a month after it forced a Ryanair flight to land in Minsk. The measures include banning EU businesses from importing goods or doing business with Belarusian companies in sectors including banking, petroleum products, and potash, a salt used in fertilizer that is the country’s main export. The sanctions are far stricter than measures imposed in the past, which had mainly consisted of blacklists of Belarusian officials and had little or no impact on the behavior of President Alexander Lukashenko, in power since 1994. EU leaders were outraged by the interception of the Ryanair plane flying between Athens and Vilnius on May 23. Belarusian authorities arrested a dissident journalist and his girlfriend after the plane landed, in an incident which Western countries branded state piracy. With Lukashenko …