Bulgaria and Romania could possibly pose an obstacle to free trade between the EU and Canada, blocking a deal that is due for discussion in the autumn, officials have suggested.

A letter by the two countries' ambassadors to the EU, quoted by the EUObserver, reads that "it would be very difficult" for the two respective governments" to find "arguments to promote the adoption" of a trade pact.

The reason cited in the letter says that "Canada is still imposing a discriminating treatment" to the two countries' citizens, in a reference to the Canadian authorities' decision not to head calls from the EU Commission for a visa waiver with regard to those EU member states still subjected to the restriction.

Canada announced in April it would not scrap visa requirements with regard to the two member states as it does not observe a principle of reciprocity on visa issues.

It is not yet clear whether Bulgaria and Romania will hold a veto power with regard to the trade deal.

There has been no immediate official reaction from EU authorities.