Kilome MP Harun Mwau has asked if former US Ambassador Michael Ranneberger filed a formal complaint on the Kenyans he had accused of various criminal economic activities.
He also questioned whether comprehensive investigations were carried out by Kenya Anti-Corruption Commission and if so, whether any action was taken.
Justice and Constitution Affairs Assistant Minister William Cheptumo said Kacc did not undertake any investigation and that the Criminal Investigation Department was the best placed to give a report on the drug trafficking investigations.
The assistant minister said the former US ambassador should have followed the right procedures to pass information to Kenyan Government departments.
Mr Mwau had questioned whether it was proper for a foreign mission to communicate directly with Government departments and not through the Ministry of Foreign Affairs.
In December 2010, late Internal Security minister George Saitoti named the MP as among those who were being investigated over alleged drug trading. (READ: Obama targets Mwau in drug war)
Others were Mr William Kabogo (Juja), Mr Hassan Joho (Kisauni) and Mr Gideon Mbuvi alias Mike Sonko (Makadara).