KHOST (Reuters) - Afghan troops shot dead three would-be suicide bombers who attempted to enter an office in an eastern city on Sunday to launch attacks on government targets, officials said. The heavily armed insurgents had explosives strapped to their chests and were killed in a 10-minute gunfight with Afghan troops outside the mayors office in Gardez, Paktia province, said Rohullah Samon, a spokesman for the provincial governor. The insurgents arrived in a car laden with explosives, which were detonated during the gunbattle, without causing injury, Samon said, adding that one state employee was killed in the crossfire. They had planned to use the office as a stage post to launch attacks on the governors compound and other key buildings in the city from an elevated position, he said. Insurgents fighting Afghan and foreign forces have previously used half-built high rises or poorly guarded buildings to stage big attacks on government targets. The most notable was the September 13 attack on Kabuls diplomatic enclave, when five suicide fighters took over an abandoned building and showered the U.S. embassy and the headquarters of NATO-led forces with rocket-propelled grenades and gunfire for 20 hours. Suicide and roadside bombings and high-profile, coordinated attacks are being used more frequently by the Taliban, with high numbers of casualties among Afghan security forces and civilians. Foreign forces say such attacks are attempts to grab media attention and avoid heavy losses sustained on the battlefield. The attack ink Gardez came a day after four suicide bombers targeted a compound housing an Afghan and U.S. military/civilian reconstruction team inside Afghanistans fiercely anti-Taliban Panjshir valley, killing two civilians. Violence is at its worst since U.S.-backed Afghan forces toppled the Taliban government in late 2001, with attacks spreading from militants strongholds in east and south to normally peaceful areas in north. The eastern region of Afghanistan has been the focus of US-led NATO efforts in recent weeks, shifting from Taliban strongholds in the south towards the restive wild border with Pakistan. The United Nations says that violent incidents in the 10-year conflict were up by nearly 40 per cent in the first eight months of this year compared to a year earlier. Suicide attacks made up a greater proportion of the violence, with three such attacks reported each month in 2011, 50 per cent more than last year. NATOs International Security Assistance Force disputes the figures, saying that by its tally violence is down by two per cent over the same period.