Former UK Prime Minister David Cameron quit the parliament on Monday, about three months after he resigned as the country's leader over June's EU referendum which had paved way for Brexit.

A by-election is expected in Oxfordshire, Witney, to fill his position since he stepped down from his seat of MP in the area.

"In my view, with modern politics, with the circumstances of my resignation, it isn't really possible to be a proper backbench MP as a former prime minister," Cameron said.

"I think everything you do will become a big distraction and a big diversion from what the government needs to do for our country."

Just 16 months ago, Cameron registered an overwhelming victory in the general elections for the Conservative Party.

Rumors were afloat in the British media that he quit over his differences in opinion with acting Prime Minister Theresa May on grammar schools. But he denied such claims.

"There's very many good things in the policy. When I was PM we agreed to the expansion of grammar schools in areas where they already were. We set up sixth forms that were selective in our big cities as free schools. Lots of merit in the policy. Frankly I don't want to get into the wheres and whys of this individual policy," he was quoted as saying by Politics Home.

"My announcement today is not about grammar schools. There's no connection with grammar schools, it's purely one of timing."

Cameron told ITV News that he made the decision to step down as an MP after "long and hard" deliberation.

May said in a statement that she was proud to have served in Cameron's government, and that "under his leadership we achieved great things. Not just stabilizing the economy, but also making great strides in delivering serious social reform."

"His commitment to lead a one-nation government is one that I will continue," she added.

Cameron was first elected as Member of Parliament for Witney in 2001, and became a Conservative Party leader in 2005. He served as Prime Minister of the UK from 2010 to July 2016.

Cameron released a formal statement saying that he hopes to serve the country through public service even after withdrawing from the parliament.

"I now look forward to a life outside of Westminster, but hope to continue to play a part in public service and to make a real and useful contribution to the country I love," he said.