Russia's richest man Alisher Usmanov's investment in Chinese e-commerce giant Alibaba has surged more than 500% since he invested capital in the group.

The billionaire revealed to CNBC that he made big gains on investments made in Alibaba, but declined to give the exact amount. Usmanov's holding in Alibaba has not been revealed to the public.

The billionaire, who has invested heavily in the tech sector, is Russia's richest man with a fortune of $18.5bn (€14.9bn, £11.8bn), according to Forbes.

In September 2014, Alibaba conducted the largest-ever stock offering in the US, raising a record $25bn from the market. The IPO was priced at $68 a share and the price rose to sky-high levels since the offering after gaining 38% on debut.

Alibaba shares closed 0.83% higher at $110.73 on 21 November.

The head of Usmanov's asset-management company USM Advisors LLC had disclosed to Bloomberg that the billionaire had reduced his stake in Facebook to focus on Chinese companies in his portfolio of foreign investments.

In his interview with CNBC, Usmanov hinted that he sold his entire stake in Facebook and invested in low-cost smartphone maker from China Xiaomi, arguing that the company is a "future technology giant".

"They have become a major company in China, the most successful since Huawei," Usmanov said.

"We are great believers in this company and we're always prepared to make an investment into this company. We know the creator of this company very well. And we'll keep investing in such companies."

Usmanov said he is also focussing on technology investments in India, particularly in online trade.