NEW DELHI: The Centre has permitted Reserve Bank of India to print 2 billion pieces of polymer notes initially for field trials, govt informed Parliament on Monday.Minister of state for finance Pankaj Chaudhary told the Lok Sabha that the one billion pieces each of Rs 10 and Rs 20 notes, which are hard to find, will be printed for field trials and for regular issue after the trials are completed. He also ruled out any move to replace paper currency with polymer substrate-banknotes and said both will co-exist.RBI has just floated a tender to source material for the polymer notes, something that has been under discussion for nearly two decades and was cleared along with an expansion of the currency printing infrastructure, which was facing capacity constraints. Officials have indicated that it can take a few months before the new notes are launched as govt and RBI want to ensure that safety is not compromised and there is no link with the material supplied to countries such as China and Pakistan.In recent years, RBI has sought to push coins in the Rs 10 and Rs 20 denominations. Together, they accounted for nearly a quarter of banknotes in circulation at the end of the last financial year, while in terms of value the combined share was 1.4%, according to RBI data.“RBI has informed that as per international studies, the life span of polymer banknotes is significantly higher than that of paper banknotes. The introduction of polymer banknotes is currently in a preliminary phase,” Chaudhary told Parliament.