The posts, dating back to 2010, came to light just days after Alaa Abdel Fattah returned to Britain following years of diplomatic efforts by London to secure his release from detention in Egypt.

British Prime Minister Keir Starmer had said he was “delighted” Abdel Fattah had been reunited with his loved ones, but faced calls to retract his comments when the posts resurfaced.

“Looking at the tweets now — the ones that were not completely twisted out of their meaning — I do understand how shocking and hurtful they are, and for that I unequivocally apologise,” Abdel Fattah said in a post on X, responding to the criticism.

“I must also stress that some tweets have been completely misunderstood, seemingly in bad faith,” he added.

The Foreign Office had condemned Abdel Fattah’s historic posts on Sunday, describing them as “abhorrent” in a statement.

Shadow justice minister Robert Jenrick, of the opposition Conservatives, called for the activist to be stripped of his citizenship.

“If the Prime Minister really was unaware that El Fattah was an extremist, he should immediately retract his comments expressing ‘delight’ at his arrival and begin proceedings to revoke his citizenship and deport him,” Jenrick posted on X.

He was granted citizenship in 2021 when the Conservatives were in power, according to media reports.

Abdel Fattah was a leading voice in Egypt’s 2011 Arab Spring uprising.

He was detained in Egypt in September 2019, and in December 2021 was sentenced to five years in prison on charges of spreading false news.

He went on hunger strike this March whilst behind bars and was later released after being pardoned by Egyptian president Abdel-Fattah el-Sisi.