A spokeswoman for the Reagan presidential library confirmed the former first lady's death on Sunday, and said she would be buried next to her husband, who died in 2004, at the library in Simi Valley, California.

Republican politicians and presidential candidates were quick to praise Reagan.

"Nancy Reagan will be remembered for her deep passion for this nation and love for her husband, Ronald. The Reagan family is in our prayers," Sen. Ted Cruz wrote on Twitter.

"Nancy Reagan was an exemplary First Lady and woman. She will be missed. My thoughts and prayers are with her loved ones. RIP Mrs. Reagan," Sen. Rand Paul said.

Reagan became one of the most influential first ladies in US history during her Republican husband's presidency from 1981 to 1989.

The former first lady played a major role in her husband's political career, acting as the face of the "Just Say No" anti-drug campaign and serving as a confidante and adviser to the president on a host of political matters.