Maria Sharapova has been suspended from her role as goodwill ambassador by the United Nations Development Programme (UNDP)

Former world number one Sharapova was provisionally suspended from March 12 after testing positive for meldonium at the Australian Open in January.

The Russian said she had been taking the substance for 10 years due to health reasons and was unaware it had been added to WADA's list of prohibited substances on January 1.

Nike, TAG Heuer and Porsche have all subsequently postponed commercial relations with Sharapova, who has now been suspended from the ambassadorial role she has held since February 2007.

"The UNDP remains grateful to Maria Sharapova for her support of our work, especially around the Chernobyl nuclear disaster recovery," a statement read.

"However, in light of Ms. Sharapova's recent announcement, we last week suspended her role as a goodwill ambassador and any planned activities while the investigation continues. We wish Ms. Sharapova the best."

The UNDP aims to eradicate poverty and reduce inequality on a global scale and operates in roughly 170 countries and territories.