The Pakistan Industrial and Traders Association Front (PIAF) has revealed its concern over non-payment of sales tax refund, customs rebate and income tax refund despite improvement in tax collection. Front Chairman Irfan Iqbal Sheikh speaking to a delegation of traders and industrialists on Tuesday urged the Federal Board of Revenue to immediately release the refunds worth billion of rupees. "Because of a liquidity crunch, businessmen are forced to close down their industrial units which in turn have increased the unemployment.