British Prime Minister David Cameron has set out four key objectives he wants to achieve in renegotiating United Kingdom's membership of the European Union. Cameron, speaking at Chatham House in London, threatened to withdraw his country from the 28-member bloc if his reform proposals were not accepted.

"I have every confidence that we will achieve an agreement that works for Britain and works for its E.U. partners," he said on Tuesday, according to Indian Express. "I have no doubt that with patience, with goodwill, with ingenuity, it can be done."

"And that in doing so, we can make Britain and the whole of Europe safer and more prosperous for generations to come," Cameron added.

[Read full text of his speech HERE.]

The British premier has also written a letter to European Council President Donald Tusk outlining his proposals to reform the U.K.'s European Union membership. His demands focus on four key points: Protection for non-euro countries, greater competitiveness, end obligation to 'ever closer union' and benefit restrictions, according to BBC.

"Today I am writing to the president of the European Council setting out how I want to address the concerns of the British people...and why I believe that the changes that Britain is seeking will benefit not just Britain, but the E.U. as a whole," said Cameron, according to Spectator.

The E.U. Commission quickly rejected Cameron's proposals, describing some of his demands to reform the E.U. "highly problematic," according to Independent.