09/08/2013 02:46 EDT | Updated 11/08/2013 05:12 EST

Mayor Nenshi, Ezra Levant in Twitter tiff over Pembina contract

Calgary's Mayor Nenshi and Sun News personality Ezra Levant sparred on Twitter Sunday morning over questions related to a contract the city has with the Pembina Institute.

- City contract with Pembina Institute improper, tax group says

- Pembina Institute defends city hall contracts