Nigerian Nobel Laureate Prof. Wole Soyinka has revealed that the United States government revoked his visa and barred him from entering the country.

Soyinka, 91, said he was invited by the US consulate to bring in his passport so the visa could be cancelled, describing the notice as a “rather curious love letter from an embassy.”

The writer, who once held permanent residency in the US but renounced it in 2016 after Donald Trump’s election, linked the action to his recent remarks comparing Trump to former Ugandan dictator Idi Amin.

The US embassy declined to comment on the case.