The US Treasury Department in 2008 used the term crony to describe the relationship of Ms Nalinee and three other persons with President Mugabe. The move culminated in Ms Nalinee's assets in the US being frozen and Washington banned her from doing business or conducting any financial or commercial transactions with US citizens.
The opposition leader said both Ms Yingluck and Ms Nalinee should clarify the matter to the public.
The premier earlier defended her decision on Ms Nalinee’s posting, saying that her qualifications as an appointee had been checked and met all the Thai constitutional requirements.
Ms Nalinee told local media that she had known the Mugabes for more than a decade, but denied she had ever had a business relationship with them.
Mr Abhisit however noted there are many people qualified for the job and questioned why the government decided to appoint "person with trouble".
The opposition leader said although there is no problem in legal terms, but it is about "appropriateness" and the premier should take clearer stance on this.
With the US statement, it is understood that any internationally-related work of Ms Nalinee as well as the image of the Thai government will be affected, the former prime minister commented.
The U.S. Department of the Treasury's Office of Foreign Assets Control (OFAC) in Nov 2008 designated four Mugabe regime cronies and a number of entities owned or controlled by two of them. It said the financial and logistical support they have provided to the regime has enabled Robert Mugabe to pursue policies that seriously undermine democratic processes and institutions in Zimbabwe.
“Those designated include John Bredenkamp, a well-known Mugabe insider involved in various business activities, Muller Conrad Rautenbach, a Zimbabwean businessman who has maintained close relations with the Mugabe regime, Nalinee Joy Taveesin, a Thai businesswoman who has facilitated a number of financial, real-estate, and gem-related transactions on behalf of Grace Mugabe, and Mahmood Awang Kechik, a Malaysian urologist and one of Robert Mugabe's physicians and business advisors.”
Dated and issued four years ago, the statement said that "ironically, Nalinee Taveesin has participated in a number of initiatives on corruption and growth challenges in Africa and Southeast Asia while secretly supporting the kleptocratic practices of one of Africa's most corrupt regimes.”