ATHENS—Greece has offered to share its experiences on migrant issues with Lithuania as it handles a sharp rise in the number of people crossing its border, Prime Minister Kyriakos Mitsotakis said on Thursday, after what he called an “orchestrated effort” by Belarus to pressure its neighbor. The comments, following a meeting with Lithuanian Prime Minister Ingrida Simonyte in Athens, come as Lithuanian and EU officials have accused Minsk of using illegal migrants to pressure the European Union because of the bloc’s sanctions. “What Belarus is doing is simply unacceptable,” Mitsotakis said, adding that the leaders had discussed how to ensure proper reception facilities, speed up asylum procedures, and also how to “effectively and quickly return those not entitled to international protection.” Amid rising tensions between the European Union and Belarus this year, more than 1,700 people have crossed the border into Lithuania, including 1,100 in July alone. “The total number …