london britain soon repay decades-old debt 400 million pound 527 million iran iranian ambassador say friday add payment link case british-iranian charity worker jail iran outstanding debt owe u.k. tehran transfer central bank iran come days payment ... nothing nazanin zaghari-ratcliffe case hamid baeedinejad write telegram channel zaghari-ratcliffe detain april 2016 tehran try leave iran visit two-year-old daughter sentence five years prison iranian court convict plot overthrow clerical establishment deny charge britain call release iran recognize dual citizenship nationals britain debt iran date 1970s islamic revolution 1979 topple u.s.-backed shah iran pay front 1,750 chieftain tank vehicles never deliver sanction impose tehran revolution british government official ask name say friday speculation money would pay treasury say statement money freeze british court could pay sanction telegraph newspaper report thursday britain work plan pay iran debt part efforts secure release zaghari-ratcliffe thursday british prime minister theresa may spokesman deny link debt charity worker case tehran also dismiss telegraph report zaghari-ratcliffe project manager thomson reuters foundation charity organization independent thomson reuters operate independently reuters news 2009 international chamber commerce order britain repay iran undelivered vehicles un eu sanction prevent deal iran six major power 2015 sanction iran lift last year exchange tehran curb nuclear program iran foreign ministry spokesman say range issue would discuss britain visit tehran month foreign secretary boris johnson iranian media report thursday britain pay 400 million-pound debt iran soon iranian envoy say