Two Chinese nationals have been arrested in Hungary and are awaiting extradition to the U.S., where they face charges of seeking to buy microchips banned from export to China, state media said on Wednesday.

The case could become another irritant in Sino-U.S. relations, which have been tested over issues ranging from China's currency to Taiwan, Tibet, China's huge trade surplus and most recently, the South China Sea, where China and several Southeast Asian countries have contending territorial claims.

Xian Hongwei and an associate were "set up" by a U.S. undercover agent and lured to Hungary, where they were arrested on Sept. 1 at the request of the U.S. government, the China Daily said.

The pair sought to buy 40 microchips that could be used for military and aerospace purposes, the Legal Daily said.

They face charges of violating international weapons sales because the product they sought is listed on the International Traffic in Arms Regulations, a U.S. government statute that seeks to curb arms proliferation, the China Daily said.

Hungarian authorities denied the pair access to the Chinese Embassy before a Hungarian court held a hearing and forced them to accept a court-appointed lawyer, the China Daily said.

Yang Daliang, spokesman for the Chinese Embassy in Budapest, told the China Daily that the embassy was "doing our best" to protect the rights of the pair and fight the extradition.

The Chinese Foreign Ministry and the U.S. Embassy in Beijing declined to comment. The Hungarian Embassy could not be reached. China and the United States have accused each other of stealing commercial and trade secrets, which can save competitors millions of research and development dollars by providing them with shortcuts.

In August, U.S. prosecutors said Kexue (John) Huang, 45, formerly a research scientist at Dow AgroSciences , a unit of Dow Chemical in Carmel, Ind., was charged with economic espionage intended to benefit China's government and transportation of stolen property.

The United States called on China in July to release Xue Feng, a U.S. geologist born in China, who was jailed for eight years for stealing state secrets after negotiating the sale of an oil industry database to his employer at the time, Colorado-based consultancy HIS Energy, now known as IHS Inc.

In February, a California court jailed Dongfan "Greg" Chung, a naturalized U.S. citizen and ex-Boeing Co engineer, for 15 years for passing space shuttle secrets to China in America's first conviction under a 1996 espionage law.

Yu Xiangdong, who worked for state-owned Beijing Automotive Industry Corp, China's fifth-biggest automaker, was arrested in the United States in 2009 and accused of stealing trade secrets from Ford Motor.