OTTAWA, June 7 (Reuters) - The Teamsters union said on Friday that Canadian National Railway and Canadian Pacific Kansas City had rejected a proposal to stagger negotiations with both companies by two weeks, which would reduce the economic disruption from a strike or lock-out.

"(Their) rejection of this proposal is a clear indication of ... their unwillingness to negotiate," Teamsters Rail Conference Union President Paul Boucher said in a statement. The two sides are at an impasse after more than five months of talks on a new contract. (Reporting by David Ljunggren)