LONDON, Jan 20 (Reuters) - Britain on Thursday turned down a planning application for a high-voltage undersea power cable project linking Britain and France. The project, run by investment firm Aquind, aims to link the power grids of Britain and France to make energy markets more efficient, improve supplies and greater flexibility. British Business Secretary Kwasi Kwarteng made the decision to turn down planning, according to government documents. "The Secretary of State has ... decided, in accordance with Section 104(3), to refuse development consent," the documents said. Kwarteng disagreed with an earlier planning authority assessment of the project. Thursday"s document included technical reasons linked to the consideration of alternative routes which meant Kwarteng could not be certain that the need for and benefits of the development would outweigh its impacts. Aquind said it would consider challenging the decision. "We disagree with the decision of the Secretary of State, and the rationale behind it. We are considering the decision, the grounds for the refusal, and a potential legal challenge," a spokesperson said in an emailed statement. The decision can only be challenged through a judicial review, a letter setting out the government decision said. A judicial review involves asking a court to rule on the lawfulness of a decision taken by a governing body. Aquind says its undersea cable linking England and Normandy would be able to transmit 16,000,000 MWh of electricity each year - up to around 5% of Britain and France"s total annual consumption.