“With enormous sadness, in our name and on behalf of the family, we regret to announce that our great author and friend Javier Marias passed away this afternoon in Madrid,” Alfaguara wrote.

The publisher’s statement said he had been suffering “for several weeks from pneumonia which worsened in recent hours”.

The El Mundo daily said the pneumonia was “caused by Covid-19” and that the author had been hospitalised for months.

According to “El Pais” daily, he underwent an operation on his back shortly before the pandemic.

Born on Sept 20, 1951, the Madrid-based writer, considered one of the great authors in contemporary Spanish literature, published his 16th novel “Tomas Nevinson” last year.

His best-known works include “All Souls”, “Tomorrow in the Battle Think on Me”, and “A Heart so White”, which brought him critical acclaim in the 1990s.

A member of the Royal Spanish Academy of language since 2008, Marias spoke fluent French and English.

As a columnist who used to write for the weekly magazine of Spain’s leading “El Pais” daily, he railed against politicians of all stripes, and once described Spain’s then prime minister Mariano Rajoy as an “airhead”.

A passionate film and Real Madrid fan, he was also, despite his republican principles, the “ruler” of a fictional kingdom based in the real, uninhabited islet of Redonda in the Lesser Antilles.

Marias was handed the imaginary title, which has been passed from one writer to the next, after he wrote “All Souls” – although there were other contenders to the throne.

“It is only a title. The island was recovered by Antigua, it belongs to Antigua, and I am not going to have dynastic disputes about anything that is more fictional than real,” he told “The Paris Review” literary magazine in 2006.

Still, Marias took on the mantle of king – with a dash of tongue-in-cheek – naming Spanish filmmaker Pedro Almodovar “Duke of Tremula” and US director Francis Ford Coppola “Duke of Megalopolis”.