UPDATE 2-Channel Tunnel reopens after smoke alert

* Eurotunnel reopens after smoke detector sparks alarm

* No fire found, train service returns to normal

(Adds service returning to normal)

PARIS, May 15 (Reuters) - The Channel Tunnel was reopened on Saturday after a smoke alert forced the closure of the rail link that connects Britain to continental Europe, Eurotunnel (GETP.PA) said.

Eurostar trains faced delays of between one and three hours during the morning, French railway operator SNCF said, but the service was operating normally by early afternoon.

Sensors detected smoke at around 0800 GMT when a shuttle transporting lorries was travelling through the tunnel. Around 30 passengers and crew were evacuated from the train and traffic was halted as engineers checked the system.

"No fire was detected, there was just a slight presence of smoke," a Eurotunnel spokeswoman said. "Rail traffic returned to normal by the beginning of the afternoon," she added.

Eurotunnel, which operates the Channel Tunnel, has a comprehensive system of sensors along the length of the 50-km (30 miles) undersea link to detect any sign of smoke or fire.

A blaze on a freight train in September 2008 took almost 20 hours to put out and a full rail service was not resumed until the following February after extensive repairs.

There was further severe disruption at the end of last year, when cold weather caused the trains to break down in the tunnel, leaving thousands of passengers stranded. (Reporting by Crispian Balmer; Editing by Louise Ireland)