TORONTO — Former Canadian politician and diplomat Stephen Lewis died at age 88, the Stephen Lewis Foundation announced Tuesday. Lewis, who had been diagnosed with stomach cancer eight years ago, died of cancer.

Lewis served as Canada's ambassador to the United Nations for four years after Prime Minister Brian Mulroney appointed him to the post in 1984. After his tenure as ambassador, he held multiple posts with the United Nations, including serving as a special adviser to UN Secretary-General Kofi Annan.

Lewis was elected to the Ontario legislature in 1963 at the age of 26. He became leader of the Ontario New Democratic Party in 1970 and led the party to official opposition status in 1975. He resigned as party leader in 1978.

After resigning from provincial politics, Lewis worked as a media commentator, lecturer, and labor arbitrator before his appointment as UN ambassador. Following his ambassadorial service, Lewis served as special adviser to the United Nations secretary-general on African affairs until 1991.

Lewis was deputy director of UNICEF from 1995 to 1999 and served as the United Nations special envoy for AIDS in Africa from 2001 to 2006. Throughout his career, he advocated for human rights, equality for women, and African families affected by AIDS. He also warned about the threat of climate change and spoke out against physical and sexual violence against women and children.

Lewis focused global attention on the HIV/AIDS epidemic during his work with the United Nations. He began working for the federal New Democratic Party early in his career and remained a social activist throughout his life.

Lewis was married to journalist and social activist Michele Landsberg. The couple had three children: Ilana Landsberg-Lewis, Jenny Leah Lewis, and Avi Lewis. His son Avi was elected leader of the federal New Democratic Party on Sunday and is married to writer Naomi Klein.

Lewis served as a politician before his diplomatic career and worked to advocate for various human rights causes throughout his life. He held positions at multiple international organizations focused on global development and humanitarian issues.