The Ministry of Foreign Affairs urged countries where Chinese fugitives are hiding to discard prejudice and work more closely with China in its massive anti-graft drive, a senior official said on Wednesday.

China has concluded 39 extradition treaties with countries, and 29 are in effect, said Xu Hong, director-general of the ministry's Department of Treaty and Law.

Of the 52 criminal judicial assistance treaties that China has signed with countries, 46 are in force, but "tremendous challenges" remain, he said at a news briefing in Beijing.

Some countries have adopted "a passive attitude" about signing extradition treaties with Beijing, and some are prejudiced against China and refuse to extradite or repatriate suspects, Xu said.

The United States and Canada, the most popular destinations for Chinese officials accused of corruption, have yet to sign extradition treaties with China.

According to the Ministry of Public Security, at least 150 Chinese economic fugitives, many of them corrupt officials, are hiding in the US. From 2003 to 2013, just two suspects wanted on criminal charges were repatriated.

Xu said China has tried to persuade the US to sign an extradition treaty, but Washington "does not seem ready".

The US government can only cooperate when an extradition treaty has been signed, "so, in this case, we can only think of other methods," he said.

"One way may be to repatriate suspects through laws covering illegal immigration; the other is to prosecute them in the US, so the suspects can be tried under US law."

Differences in social and legal systems mean that some foreign judges have an insufficient understanding of the Chinese legal system, or are prejudiced and so are reluctant to return officials suspected of corruption, said Xu.

Huang Feng, a law professor at Beijing Normal University, said the US Congress, whose approval is needed for an extradition treaty to take effect, believes that China does not offer suspects sufficient guarantees that their rights would be protected or ensure that they would receive a fair trial.

"A treaty would be mutually beneficial, as there are US fugitives in China, too," said Huang. "The pledges by leaders at the recent APEC and G20 meetings could help the process."

The APEC economic leaders' meeting earlier this month established a regional law enforcement cooperation network to crack down on corrupt officials.

Sun Ang, special coordinator for fugitive repatriation and international law enforcement cooperation under the ministry, highlighted progress made by China and the US in hunting fugitives and recovering illicit assets under the China-US Joint Liaison Group on Law Enforcement Cooperation framework.

During a seminar in October, both countries agreed to enhance cooperation in investigating, tracing, freezing, recovering and returning assets gained by corruption, said Sun.

China and Canada completed negotiations on an agreement covering the sharing and returning of forfeited assets in June 2013. It was the first special agreement that China has negotiated with another country on recovering illicit assets.

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