The 11th round of Bilateral Investment Treaty (BIT) talks between the world's two largest economies, China and the US, wrapped up in Shanghai on Wednesday.

The talks, which experts say could still take a year or two to finalize, are expected to knock down existing hurdles and further open up the markets to both sides.

"Negotiations are going smoothly, though disparity of opinion exists," Li Chenggang, director of Department of Treaty and Law of Ministry of Commerce, was quoted as saying by China National Radio on Wednesday.

Both parties had reached a consensus to take a proactive, pragmatic and cooperative attitude to push forward the negotiations, out of respect for investor protection and government regulation, Li said.

Gao Hucheng, the minister of commerce, said that BIT had entered into "substantive negotiations," according to China Central Television on Wednesday.

"Bilateral trade value between China and the US has reached $500 billion, which was hard to imagine a dozen years ago. Having different opinions, contradictions or even conflicts between such large economies is normal," Gao said.

BIT made major progress in July last year when China adopted a globally-recognized approach to talks on the basis of pre-establishment national treatment with a negative list.

A pre-establishment national treatment indicates that foreign investors are entitled to treatment no less than those of domestic firms in establishment and development, while a negative list approach means that investors can invest in any sectors not explicitly stated on the list.

This new round of talks came after China's new leaders pledged to introduce significant economic reforms to further open its market and let the market play a decisive role.

Differing from the negotiations in the past, this round of talks addresses details such as which sectors will be granted equal market access to foreign investors, said He Weiwen, co-director of the China-US-EU Study Center under the China Association of International Trade.

"BIT is aimed at providing a legal system protection for a fair and transparent investment in both countries," he said. However, talks are not expected to reach a final agreement any time soon, he noted.

The US needs to guarantee the fairness and transparency in national security scrutiny on Chinese firms, Yang Yu, a CCTV commentator wrote on his Sina Weibo Wednesday.

A number of Chinese companies including Huawei and Sany had encountered setbacks in the US for allegedly threatening national security.

Difficulty remains in intellectual property rights protection and fair competition policies, said Huo Jianguo, director of the Chinese Academy of International Trade and Economic Cooperation under China's Ministry of Commerce.

In terms of market access, the service sector, and specifically financial service, insurance, education and healthcare might be the focus of the talks, Huo said.

Currently China has a list of sectors in which foreign firms cannot invest, or have to do so in a joint venture with a Chinese company, including autos and much of financial services.

China's investment in the US reached $3.65 billion, growing 232.2 percent in the first 11 months of 2013 from a year earlier, meanwhile US investment in China is $3.16 billion, up 8.6 percent year-on-year.