Russians poisoned Canadian MP in 2006, then invited him back. Embassy apologized: 'It won't happen again'
You can hear Liberal MP Irwin Cotler (one of 13 Canadians who have now been officially barred from visiting Russia in retaliation for Western sanctions against Putin cronies) describe the Russian government's attempt to assassinate him in 2006 at the CBC's web site.
In 2010, after declining an invitation to revisit Russia:
...Mr. Cotler made
a half-joking reference to being poisoned. He says that the embassy
responded: "Sorry about that. It was a mistake. It won't happen again."