The firms who have won the world's first commercial wave and tidal power leasing deals will be announced by First Minister Alex Salmond on Tuesday.

The companies will have development rights for marine renewable energy projects in the Pentland Firth and Orkney Waters.

A Scottish Government spokesman said: "We've described the Pentland Firth as potentially being the Saudi Arabia of wave and tidal power."

Mr Salmond will be joined at today's launch by Rob Hastings of the Crown Estates, who are handing out the leases.

The waters around the Pentland Firth have a potential of one giga watt of wave and tidal energy potential.

There are currently about seven giga watts of renewable capacity installed, under construction or consented around Scotland, according to the Government. Scotland's peak electricity demand is six giga watts.

The only wave and tidal energy machines currently operating in Scotland are in Orkney.

The ‘Oyster’ system became the world’s first hydro-electric wave machine when it was made operational last November.

BACKGROUND

• World's first wave energy machine goes online
• Scots companies urged to seize wave power

A Government spokesman added: "This will, when it's all up and running, take Scotland beyond our interim target of 31% of our electricity demand coming from renewables by 2010."

Green co-leader Patrick Harvie said today that appropriate government support can help marine energy to start displacing "out-dated generation systems" like coal and nuclear power.

He added: "Earlier this year, Greens persuaded Scottish ministers to establish a £10million fund to help wave and tidal power companies get their products to market.

"Investment now will bring costs down and allow the industry to become truly competitive internationally. It will also allow us both to meet our climate targets and export clean power to neighbouring countries."