Andrew Mitchell, Conservative MP for Sutton Coldfield, has written to Hilary Benn, the international development secretary, urging him to intervene in the case, which could see the charity closes and its directors imprisoned.
Inter Care has been collecting unused prescription medicines that are returned to GPs in the UK and sending them to health centres in Ghana, Cameroon, Malawi, Tanzania, Zambia and Sierra Leone for 32 years. Earlier this year, however, it was forced to suspend its work after the Environment Agency warned it this activity was illegal.
The agency classifies returned drugs as 'waste' that needs to be disposed of in landfill sites.
Margaret Macdonald, chief executive of Inter Care, is due to attend an interview at the Environment Agency under caution to discuss the case.
A representative of Inter Care's trustees will also be interviewed.
According to Mitchell, who is the Tories' shadow minister for international development, the Environment Agency's response is the result of an "overly zealous" interpretation of EU directives.
"Inter Care assures me that it follows all of the World Health Organisation's guidelines strictly," he said.
Jane Austin, resource manager at Inter Care, said: "There is an organisation called Cyclamed in France that is doing this on a huge scale - some of it medicines actually go to the homeless in France as well as to the third world."
The Environment Agency declined to comment, citing legal reasons.