work vt.

「読売新聞」がスクープした中国大使館１等書記官による外国人登録法違反事件で、スパイとみられるこの書記官が農産物の対中輸出促進事業に関する農水省の機密文書に関与していた疑いがあることが分かりました。

Police had eye on China official / Senior diplomat thought to be one of China's leading experts on Japan

The first secretary of the Chinese Embassy in Tokyo, who was attached to China's spy agency and can speak Japanese like a native, has been closely monitored by Japan's counterintelligence police since beginning his stint in Japan.

The Metropolitan Police Department's Public Security Bureau asked him to come in for questioning, but the diplomat, 45, left Japan last Wednesday.

The first secretary, who came from the second division of the General Staff of the People's Liberation Army (PLA), studied at the Matsushita Institute of Government and Management, where he apparently built a network of contacts with would-be politicians.

According to police, he graduated from a PLA foreign language institute in June 1989, and joined the General Staff of the PLA. In May 1993, he claimed to be an official of Luoyang, the sister city of Sukagawa, Fukushima Prefecture, and came to the country as a member of an exchange program between the cities.

He stayed in Fukushima Prefecture for about four years and studied at Fukushima University's graduate school from April 1995 through March 1997, working a research paper on Japan-China relations.

http://www.yomiuri.co.jp/dy/national/T120529003737.htm

work on~はよく知られている言い回しで、どちらかというとニュートラルなworkの使い方です。
しかし、work a research paper on Japan-China relationsのように「ある一定の場所、領域、または専門で作業する」という意味の他動詞 workが使われると、「日中関係に関しての専門的な論文作成の活動に従事していた」というニュアンスが伝わります。スパイ疑惑を意識した動詞の選択でしょう。（UG）