MONTREAL (Reuters) - Canadian plane and train manufacturer Bombardier Inc (>> Bombardier, Inc.) took big hits to prospects for growth in its core units this week, putting it under increased pressure to find new markets for its jets and a potential new train maker partner.

On Tuesday, the U.S. imposed preliminary anti-subsidy duties that would effectively block Bombardier jet sales in a key market if upheld.

Meanwhile, Germany's Siemens AG (>> Siemens) opted to merge its rail business with France's Alstom SA (>> Alstom) instead of Bombardier's Berlin-based rail unit.

However, the Canadian plane and train maker is still pursuing talks on jet sales to China, potential European jet orders, and a $33 billion train order backlog which may help keep its turnaround plan on track.

With C$9 billion in debt and future orders of its CSeries jet in the United States possibly blocked, some say Bombardier may face pressure to raise money to compete on its own against a newly-created European rail giant.

"They (Bombardier) need fresh money," said Maria Leenen, chief executive of German rail consultancy SCI Verkehr. "They will have to defend that (their turf) against the strong new player."

Analysts and company insiders see the potential U.S. duties on its flagship jet program as a bigger risk than the failed European rail merger.

Bombardier is in a stronger position than it was in 2015, when it considered bankruptcy after the CSeries program fell behind schedule and sucked up capital. Cash infusions from the Quebec government in the CSeries plane production, and by Quebec's pension fund in the rail business, helped it buy time to launch a turnaround program.

But Bombardier is once again facing uncertainty that will weigh on its share price. The stock fell 14 percent on Wednesday before recovering to close down 7.49 percent at C$2.10.

"The transformation plan requires that the company continue to ramp production and deliveries of the CSeries," said Raymond James transportation analyst Steve Hansen.

"In the short term that's not an issue, but I'd say over the medium term it is an issue and they will want to be able to sell to some of these U.S. airlines."

With the U.S. market in doubt for now, Bombardier is pushing hard for its first CSeries sale in China. A senior Bombardier executive told Reuters on Tuesday that it aims to close deals with Chinese airlines in coming months.

Sources said Canadian Prime Minister Justin Trudeau will soon visit China, where part of the CSeries fuselage is made, suggesting deals could be announced. Officials familiar with the plan say it is likely to take place in December.

"There’s an excess of 56 carriers in China but five to six are really big," said Robert McWhirter, president and portfolio manager at Selective Asset Management in Toronto. "If they standardize on some of the Bombardier airframes, then most of the problems are solved."

Meanwhile, rail unit Bombardier Transportation (BT) may need a partner at some point to compete against the new European giant created by the deal between Siemens and Alstom and China's merged rail behemoth, CRRC Corp Ltd. (>> CRRC Corp Ltd). For now, it has the heft to stand alone, analysts and company insiders say.

"Suddenly the chess board has changed but Bombardier is not small," said a source familiar with the matter.

In addition, BT can scoop up contracts in the near-term while Siemens and Alstom focus on integrating their businesses.

Trade experts are not convinced that Boeing's CSeries trade complaint will be upheld in 2018 by an independent U.S. trade body currently composed of four commissioners from both American political parties.

The International Trade Commission (ITC) will decide whether the CSeries, which was sold to Delta Air Lines (>> Delta Air Lines, Inc.), and are to be delivered in 2018, harmed Boeing, which did not compete for the order with one of its planes.

"There's a real question as to whether the Commission will determine a company to be threatened with injury when it doesn't produce a directly competing project," former ITC chairman Dan Pearson said by email. "And the actual delivery of aircraft ... is at least a couple years away."

(Reporting By Allison Lampert; editing by Clive McKeef)

By Allison Lampert