The U.S. Food and Drug Administration said on Friday it expects China, after almost two years of delays, to soon approve visas that will allow the agency to more than double its staff in China.

"We're heading into the homestretch," Margaret Hamburg told reporters on a conference call, when asked how soon China might approve the visas, which would more than triple the number of U.S. civil servants it posts in Beijing.

Hamburg gave the optimistic assessment ahead of her planned visit next week to China, when she will meet with Chinese health regulators in an effort to further improve oversight of foods and drugs that are exported to the United States.

Later on Friday, an FDA spokesperson said the agency expects the visas to be approved "in the coming weeks and months."

The FDA has 13 employees in its Beijing office, including eight U.S. citizens and five Chinese staff. When fully staffed, it would include 26 U.S. civil servants and seven Chinese staff.

The U.S. agency wants to increase the number of its food and drug inspectors, and other officials who can interact with the China Food and Drug Administration. The planned new hires were authorized and funded by Congress in 2013.

Hamburg's comments came two days after President Barack Obama, during his own visit to China, criticized the country's refusal to issue visas to foreign correspondents.

China ranks seventh among countries that export drugs to the United States, and sixth among food exporters to the United States.

As China becomes a bigger player in U.S. markets, the FDA plans to more thoroughly examine the safety and effectiveness of its products, and factories where they are made.

In the last year, four of the FDA's U.S. staff in China have completed their tours of duty, and the positions have remained unfilled due to the FDA's inability to secure visas, said FDA spokeswoman Stephanie Yao. In addition, nine other Americans are preparing to take assignments in China once visas are issued, she said.