Nigeria's President Goodluck Jonathan has been given the all clear to travel after falling ill while on an official visit to London, his spokesman said Saturday.

Jonathan was forced to skip a meeting Thursday with an investment advisory group after "the sudden onset of several abdominal pains," Reuben Abati said in a statement.

"After a thorough evaluation of the president's symptoms, medically referred to as acute abdomen, the doctors concluded that no surgical intervention was required," Abati said.

The leader of Africa's most populous country will therefore leave Britain Sunday and return to Nigeria's capital Abuja, added the statement.

In an earlier statement, Abati condemned some online media outlets for suggesting that Jonathan had become ill after binge drinking at a birthday party in the British capital. The president turned 56 on Wednesday.

He said that such outlets, which "operate in the nebulous sphere of cyberspace," may face "legal action for libel and wilful defamation of the character and reputation of the president."

Abati specifically singled out the influential Sahara Reporters, a US-based blog that has broken a number of major stories, including corruption scandals involving top Jonathan allies.

"No birthday party was...held for the president in London and there was certainly no drinking spree as Sahara Reporters claimed," Abati said.

Jonathan assumed the presidency in 2010 following the death of his predecessor Umaru Musa Yar'Adua.

Yar'Adua's protracted illness, details of which were kept from the public, sparked a months-long political crisis in Nigeria.