HANOI (Reuters) -Communist-ruled Vietnam is expected to ratify this year the UN convention for the free establishment of trade unions, UN officials and diplomats said, in a move meant to cut risks of trade disputes but likely leaving some foreign companies uneasy. The long-delayed measure would be a major formal step in the tightly controlled one-party nation where the only existing national trade union operates within the Communist Party structure, although it is unclear how and when the convention, once ratified, would be actually applied. The Southeast Asian manufacturing hub, which is home to factories of international companies including Samsung Electronics, Intel, Foxconn and Canon, is highly reliant on commerce, which last year exceeded 160% of the $415 billion domestic economy.