(Bloomberg) -- The Angolan government said it was “surprised and deeply regrets” that former President Jose Eduardo dos Santos chose to fly on a Portuguese airline on Tuesday, instead of the national carrier.

Dos Santos is in Madrid for “routine” medical exams, President Joao Lourenco’s office said in an emailed statement. Officials tried “all channels of dialog to persuade” Dos Santos to use Angola’s state-run carrier, known as TAAG, but the former head “declined.”

Dos Santos led sub-Saharan Africa’s second-biggest oil producer for 38 years and handpicked Lourenco, his former defense minister, to succeed him. Lourenco pledged to fight corruption, improve governance and diminish the grip of his predecessor’s family on the economy when he took over in 2017, and relations between the leaders has become strained.

The “unheard of” public criticism of his predecessor shows that “things aren’t going well between the current and ex president,” Luanda-based political analyst Augusto Bafuabafua said by phone. “They’re showing that they distrust each other. And that’s not good.”

To contact the reporter on this story: Candido Mendes in Luanda at cmendes6@bloomberg.net

To contact the editors responsible for this story: Antony Sguazzin at asguazzin@bloomberg.net, Helen Nyambura, Gordon Bell

©2019 Bloomberg L.P.