NAREWKA, Poland—Hundreds of migrants on Tuesday camped near the Belarus-Poland border where razor wire fences and Polish border guards blocked their entry into the European Union. The EU vowed more sanctions against Belarus, accusing President Alexander Lukashenko of using “gangster-style” tactics in the months-long border stand-off in which at least seven migrants have died. Poland and other EU member states accuse Belarus of encouraging the migrants—from the Middle East, Afghanistan, and Africa—to illegally cross the frontier into the EU in revenge for sanctions slapped on Minsk over human rights abuses. “The Belarusian regime is attacking the Polish border, the EU, in an unparalleled manner,” Polish President Andrzej Duda told a news conference in Warsaw. “We currently have a camp of migrants who are blocked from the Belarusian side. There are about 1,000 people there, mostly young men. These are aggressive actions that we must repel, fulfilling our obligations as a …