By Muriel Boselli and Marion Douet

PARIS (Reuters) - The French government will launch a tender on Saturday for the construction of pilot marine energy projects to speed up the development of wave and tidal power, sources with direct knowledge of the matter said.

Later on Tuesday, Energy Minister Philippe Martin told a parliamentary hearing that the government was "shortly going to launch a tender for marine energy projects".

He gave no further details.

The 200 million euro ($267 million) tender is intended for the construction of 30 to 40 marine devices with a combined capacity of around 80 megawatts (MW) at the Raz Blanchard marine site in northwestern France, the sources said.

The pilot project should start in 2015 but full-scale production commercial production would not commence before 2020-2025 at the site, the sources added.

France has Europe's second-biggest tide potential after Britain with an electricity production capacity of 3,000 to 5,000 MW, equivalent to three to five average-sized nuclear reactors.

Britain already has 12 large-scale prototype devices with a capacity of 9 MW generating clean electricity, more than the rest of the world combined.

It is betting on the potential of marine energy, aiming for 100 to 200 MW of wave and tidal energy installed by 2020, but making the leap from prototype to fully functioning is a challenge.

High development costs have helped deter some private investors in the sector, but there are signs confidence is growing as engineering firms such as Siemens and Alstom have taken controlling stakes in a number of British manufacturers over the past year.

"We can't miss this opportunity. If we don't go for it, we are really hopeless," said Francois Piquet, head of Ouest Normandie Energies Marines, a public firm which promotes the potential of marine energies.

"Today we have the capacity to install 2,000 turbines," he said.

(Editing by Michel Rose, Nina Chestney and David Evans)