* Judge says long procurement delay not in public interest
* Eurostar says can proceed with signing Siemens contract
* Alstom says will pursue other legal options
* Alstom shares close down 0.85 percent, underperform index
(Adds judge, Eurostar, Siemens comments, detail, shares)
By Caroline Copley
LONDON, Oct 29 (Reuters) - A British court turned down French engineering firm Alstom's request to block Eurostar from finalising a 600 million euros ($832.7 million) high-speed train order with Germany's Siemens.
Alstom remained defiant after the refusal, saying in a statement late on Friday it was pursuing legal alternatives and had already submitted its case to the European Commission.
Eurostar, the sole operator of passenger trains through the Channel Tunnel, has traditionally relied on Alstom for its rolling stock. Its decision to order 10 trains from Siemens has threatened to engulf France and Germany in a protectionist row.
Alstom had asked the court to issue an injunction against the order, arguing Eurostar had breached procurement laws and that the trains it was ordering from Siemens would not comply with safety rules.
The French government has said the proposed Siemens trains are not long enough in case passengers need to be evacuated, and that their engine and power-supply layout pose a safety risk in case of fire.
But Judge Geoffrey Vos said that if the injunction was granted and Alstom's case went to trial, it would probably not be resolved until Spring 2011. A delay to Eurostar of that nature would be costly to the travelling public, he added.
"Public interest is served by the introduction of timely competition for Channel Tunnel services," Vos told Britain's High Court in London on Friday.
Alstom responded by saying in a statement Judge Vos had recognised that it had shown the case was "serious". It added it would pursue "alternative legal options" to uphold its position.
Alstom is a market leader in high-speed rolling stock and the French government has expressed misgivings about its national champion losing out in its own backyard.
Its shares extended losses following the ruling and closed down 0.85 percent at 36.26 euros while the Paris CAC 40 index ended flat. Siemens shares closed down 0.4 percent to 82.08 euros, with Germany's DAX up 0.1 percent.
"We are very pleased that the situation has been resolved and we can proceed to signing the contract for our new fleet of trains with Siemens," Eurostar said in a statement.
Deutsche Bahn, which also plans to run services through the Channel Tunnel in a bid to link London directly to Frankfurt and Amsterdam, has a 500 million euros order with Siemens for 15 ICE 3 trains similar to those ordered by Eurostar.
"We have every confidence in the legal integrity of our bid and we remain delighted that we won the (Eurostar) tender," Siemens said in a statement.
The Franco-British Intergovernmental Commission (IGC), governing the operation of the Channel Tunnel, is reviewing safety regulations on the line.
($1=.7205 Euro)
(Additional reporting by Jens Hack in Munich and Lionel Laurent in Paris; Writing by Greg Roumeliotis; Editing by David Hulmes)