Leading diamond mining firms in Zimbabwe are struggling against dwindling deposit and liquidity crunch, company sources revealed Friday, stoking fears that the mining sector boon that sustained the country's near double-digit economic growth since in the past four years might soon end.

Zimbabwe's diamond mining concentrates in the eastern region of Marange, near the border with Mozambique. There are seven companies licensed to mine diamond in Marange fields, accounting for more than 80 percent of the country's diamond output, which is estimated to have reached 11 million carats in 2013.

Diamond Mining Company (DMC), a joint venture between Pure Diamond of the United Arab Emirates and the state-owned Zimbabwe Mining Development Corporation (ZMDC), said alluvial diamond deposits at its claim were diminishing.

"Yes, they are running out. We do not have any conglomerate or kimberlitic deposits. We are mostly doing alluvial and the grade is going down. The resources are greatly depleted and we are facing a challenge in production," DMC general manager Ramzi Malik told Xinhua in a follow up interview after presenting oral evidence before a parliamentary committee.

He said the available reserves could only last them two to three years, adding that the company had since asked government for a new concession.

The government says Zimbabwe holds estimated diamond reserves of 16.5 million tonnes. But mining officials have hinted that they won't consider giving mining firms new concessions until the existing ones finish.

Anjin Investment, a 50/50 joint venture between China's Anhui Foreign Economic Construction Company and the ZMDC, also complained that it was facing serious financial problems as a result of depleting diamond reserves at its claim.

Anjin board member responsible for corporate affairs Munyaradzi Machacha told a parliamentary committee that the company, which employs about 850 people, was struggling.

"The company is in survival mode. Our resources have dwindled and we are receiving low grade. Our prices are the lowest in the Marange diamond area," Machacha said.

He said the company had asked for more diamond concessions from the government and was awaiting a response. Machacha said output reached its peak in 2011 -- 350,000 carats -- and has since then been on a decline marked by low ore and recovery grades.

"This meant we had to look for other sources of funds to keep operations going. We even had to borrow," Machacha said.

Having started operations in 2011, the company has so far produced 7.8 million carats of diamonds and sold 6.8 million of them.

It has paid 47.6 million U.S. dollars to the government in royalty and resource depletion fees.

Machacha also said the cash flow problems had seen the company failing to meet some of its corporate social responsibility programs, including meeting a pledge of 1.5 million U.S. dollars contribution to a community share ownership scheme.

Malik, meanwhile, said the company worried about misappropriation of the funds under the current uncoordinated conditions regarding the running of the local beneficiation scheme.

"There is a lot of confusion in this diamond industry. There is no coordination effort in this industry. If relevant authorities could coordinate the efforts of all companies in Marange, then we can make a big difference," Malik said.

Income of raw diamond export has been instrumental to Zimbabwe's mining sector boom since 2010. The country's growth dropped to estimatedly 3.4 percent last year. Though the government has set a goal of 6 percent growth for 2014, industries and experts have doubts over the target as there are not yet signs of a strong economic recovery.

For the diamond sector, the good news is the opening of the European market, which have barred Zimbabwean gems from trading due to long-hanging sanctions against the administration led by veteran president Robert Mugabe.

The European Union, however, removed ZMDC from its sanction list last year, enabling the Zimbabwean gems to be sold in the European market. In the first auction of Zimbabwean diamonds at Antwerp, Belgium, last December, about 300,000 carats of diamonds went under the hammer, generating 10.7 million U.S dollars. The second diamond sale at Antwerp this month raked in 70 million U.S. dollars.