A Pakistani security officer says police have arrested thousands of Imran Khan supporters ahead of a rally in Islamabad to demand the ex-premier’s release from prison. Khan has been behind bars for more than a year. But he remains popular and his party says the cases against him are politically motivated. Police Sunday arrested more than 4,000 Khan supporters in eastern Punjab province, a Khan stronghold. They include five parliamentarians. Pakistan has sealed off the capital with shipping containers. It also suspended mobile and internet services “in areas with security concerns.”