Hague pledges leading role for Tories in Europe

In a keynote speech, he sought to reassure European leaders concerned that a Tory government would see a return to the battles of the 1980s and 1990s, insisting that the party wanted to engage "energetically" with EU partners.

While he acknowledged the Tories had not shied away from "frank criticism" of the EU in the past, he insisted that they were also the "foremost champions" of the single market and EU enlargement and they would seek to "maintain and value the bonds of our relationships" with other EU states.

"The European Union is obviously an institution of enormous importance to the United Kingdom and its foreign policy," he said in his address to the Royal United Services Institute in London.

"If we win the coming General Election, it is our firm intention that a Conservative government will be active and activist in the European Union from day one, energetically engaging with our partners."

He said that they would be "highly active" in promoting European co-operation on climate change, energy security, and pressing for freer and fairer global trade, as well as pushing for Turkey's membership of the EU.

Mr Hague also emphasised the potential of the EU future 2020 strategy on jobs and growth to enhance Europe's competitiveness "if we get it right".

While the Tories had opposed the Lisbon Treaty which created the new External Action Service – effectively an EU diplomatic service – he said that they now accepted its existence and would seek to work with it.

They would also work closely with Baroness Ashton, the Labour peer who heads the service, although Mr Hague warned that she had an "almost impossible task".