Image copyright Thinkstock Image caption Wind power is expected to be the fastest growing renewable energy source in the coming decades

Scottish Power has won the right to build two offshore wind farms in the US which it says could eventually power 400,000 homes.

The two sites combined are more than double the size of the energy giant's operations in the UK.

The two farms will be off the coast of Massachusetts and North Carolina, and are expected to start generating power by 2022 and 2025 respectively.

The company refused to say how much it had paid to win the bids for two sites.

Thousands of jobs are expected to come from the development of the wind farms.

Keith Anderson, Scottish Power's chief corporate officer, said the firm's success was evidence of the UK industry's export potential.

"We as a country are seen to be the leaders in this type of technology. It's great to be creating opportunities and developing skills in the UK, but also to see these being exported.

Mr Anderson said the "huge amount of land" in the US had made "colossal wind farms possible onshore".

"The cost differential between onshore and offshore was so large that a lot of people never thought that America would be interested. But now we're staring to see the process pick up speed as the cost of offshore wind comes down," he added.