The U.N. says at least one million people in north-west Pakistan have been affected by the country's worst monsoon floods in living memory. Rescuers are struggling to reach inundated areas where transport and communication have been cut off. Peshawar, the area's largest city with a 3 million strong population, is cut off. Information minister for the Khyber Pakhtunkhwa province, Mian Iftikhar Hussain said 800 people have been killed and described the floods as the province's worst ever. The death toll may rise as large areas remain inaccessible and more rain is forecast.The government has declared a state of emergency as Pakistan's meteorological department said 312 mm of rain had fallen over the last 36 hours in the north-west – the largest amount for decades. The districts of Swat and Shangla, as well as parts of Afghanistan – where at least 60 have died – are also inaccessible. Some 45 bridges have been washed away in the Swat Valley alone. Military and rescue workers have been using helicopters to deliver essential supplies to areas that have had transport and communication links cut off. Some 17 helicopters were in action to airlift people out of the worst affected areas and more are being deployed. The army says all available troops have been deployed for relief work.