National Australia Bank sold only half the level of longer-dated, covered bonds overnight that it had aimed for, International Financing Review reported.NAB sold £250 million in 14-year covered bonds. It priced the bonds at 120 basis points over Gilts. The NAB deal was priced in the same format and with the same maturity as a £750 million covered bond sold last week by Commonwealth Bank, the Covered Bond Report noted in a commentary published this morning. CBA sold those bonds at 118 bps over Gilts.Pricing on the NAB bond widened by three basis points since launch, IFR reported.