A former education minister in Germany who resigned over plagiarism allegations has lost a legal bid to have her doctorate restored.

Annette Schavan, an ally of Chancellor Angela Merkel, quit in February 2013 after an academic panel at Heinrich Heine University in Duesseldorf reviewed her 1980 doctoral thesis, discovered uncredited passages from others' work throughout her paper, and revoked her degree.

A Duesseldorf administrative court upheld that decision Thursday. Schavan said she would read the full judgment before deciding whether to appeal it.

"I once again reject strongly the accusation of deception," the 58-year-old said in a statement.

Merkel's government plans to make Schavan, a reform-minded Roman Catholic, Germany's next ambassador to the Vatican.