KARACHI: The Federal Government has declared the old-design banknote of Rs 500, which was introduced in April 1986, shall cease to be legal tender with effect from October 1, 2011 and hence cannot be exchangeable from this date.Accordingly, the State Bank has asked the general public to exchange the old-design banknote of Rs 500 from the field offices of SBP Banking Services Corporation and the branches of all commercial banks throughout the country up to September 30, 2011.Central bank has already completed the issuance of new design banknote series of all denominations (including Rs 500), which started with the launching of Rs 20 denomination banknote in 2005, to improve the security features, durability and aesthetic quality of banknotes – Dailytimes