Cutting staff and funding for Britain's embassies in Europe and deploying additional resources in India and China are among plans outlined by Hague to diplomats and staff of the Foreign Office.
The Foreign Office has already announced that the current High Commissioner to India Richard Stagg, will be replaced by James Bevan in November.
Hague's plans include opening five new embassies in countries including El Salvador, Kyrgyzstan and South Sudan, as well as new offices in Brazil, Mexico, Turkey and Indonesia.
Hague said: "As foreign secretary I announced on day one that my objective is to ensure that there is no strategic shrinkage of Britain's influence under this government. Our diplomatic network is the essential infrastructure for our foreign policy and our influence overseas".
He told Foreign Office staff: "By 2015 we must aim to be a Foreign Office that is lean and efficient but configured to match the realities of the 21st century. Taken together, this represents the biggest strategic diplomatic advance by Britain in decades." Hague is scheduled to outline the changes in a statement in the House of Commons later today.