FILE PHOTO: British Prime Minister Boris Johnson delivers a joint statement with French President Emmanuel Macron (not seen) before a meeting on Brexit at the Elysee Palace in Paris, France, August 22, 2019. REUTERS/Gonzalo Fuentes/File Photo

LONDON (Reuters) - British prime minister Boris Johnson was stable overnight in intensive care after suffering a deterioration of his COVID-19 symptoms and he remains in good spirits, his spokesman said on Tuesday.

The spokesman told reporters the prime minister, who was admitted to hospital on Sunday, was receiving standard oxygen treatment and was breathing without any other assistance. He did not require a mechanical ventilator.

“The prime minister has been stable overnight and remains in good spirits. He is receiving standard oxygen treatment and breathing without any other assistance. He has not required mechanical ventilation, or non-invasive respiratory support,” the spokesman said.