KABUL - Afghan security forces shot dead at least one would-be suicide bomber on Sunday in a high-security area of Kabul, home to government departments and diplomatic missions, police said.Violence across the country has increased over the last 12 months, sparking concern about how the 350,000-strong Afghan security forces will manage once most foreign troops withdraw by the end of 2014.The shooting happened near a construction site that was stormed by Taliban gunmen in April last year. They began a nine-hour attack, firing rockets at western embassies and nearby hotels frequented by foreigners.The man shot dead on Sunday was parked in a four-wheel-drive in the suburb of Sherpur, when officers from the National Directorate of Security (NDS) fired at his car, killing him.There were unconfirmed reports that another attacker had escaped.The would-be bomber was armed and wearing an explosive-laden vest when he was shot dead, Kabul police chief General Ayoub Salangi told Reuters.