LONDON - British Treasury's commercial secretary Jim O'Neill has expressed his optimism about China's economic growth despite the world's second largest economy slowed to a 25-year low of 6.9 percent in 2015.

China is definitely still on track in terms of its real GDP growth, said O'Neill, who is known for the creation of BRICs acronym, which refers to emerging economies of Brazil, Russia, India and China. The grouping came to be known as BRICS after the inclusion of South Africa in 2010.

China's 6.9 percent growth is the equivalent to India growing by nearly 35 percent or the United Kingdom growing by nearly 22 percent. So 6.9 percent is the envy of any developed country, he said in an interview on Monday.

"So in sense of this real growth rate, I don't think there is anything to be worried about. The evidence of a very weak inflation or some modest size of deflation that's still more concerning. But in sense of real growth, I think it is fine," he added.

If China's annual growth rate would be 6.3 percent for the rest of the decade, the country would grow by 7.5 percent for the decade as a whole, according to the former Goldman Sachs economist.