OTTAWA, May 13 (Reuters) - The western oil- and

grain-producing province of Alberta on Monday urged Canadian

Prime Minister Justin Trudeau to do all he could to head off

potentially devastating strikes by railway and port workers.

Staff represented by the Teamsters union voted

overwhelmingly this month to strike as early as May 22. Railways

are critical to Canada's economy, due to its vast geography and

exports of grain, potash and coal.

Further to the west, talks between management and unions at

the port of Vancouver have hit an impasse.

"Any work stoppage affecting our railways and ports would be

crippling for our national economy and North American supply

chains," Alberta Premier Danielle Smith said in a letter to

Trudeau that was released by her office.

Smith said Ottawa had to do all it could to help the parties

in both disputes reach negotiated settlements.

"In the event of a work stoppage, your government must be

prepared to use all the tools at its disposal to terminate it

rapidly, including, if necessary, back-to-work legislation,"

said Smith, one of Trudeau's main domestic political opponents.

The ruling center-left Liberals could present a draft law to

force striking workers back to work but in the past have shown

little interest in doing so.

Asked about a possible Vancouver port strike, the office of

Labour Minister Seamus O'Regan said: "Our government believes in

collective bargaining." O'Regan last week asked the Canada

Industrial Relations Board to look at whether a rail strike

might have safety implications.

Until the board has issued a decision, the strike by workers

at Canadian National Railway ( CNI ) and Canadian Pacific Kansas City ( CP )

cannot start. The board on Monday asked for submissions by the

end of business on May 21 and could take weeks to act.

The unions are currently negotiating contracts and asking

for better wages and working conditions.