Kenya has asked international police agency Interpol to issue a red alert for a British woman known as the "white widow."
Samantha Lewthwaite has previously been linked to the al-Shabab group behind Kenya's shopping mall attack in which 67 people were killed.
Interpol did not link the warrant to the Nairobi attack.
The charges relate to being in possession of explosives and conspiring to commit a felony and date back to December 2011.
Ms Lewthwaite was married to one of the suicide bombers involved in attacks on London's transport network in 2005 which killed 52 commuters.
She publicly denounced her husband and was granted police protection.
Meanwhile, more funerals have been held for victims of the Kenyan attack and forensic teams are continuing to scour the shopping complex.
Kenya's interior minister has said he does not expect the death toll to rise significantly, and believes only the bodies of militants will be found, the BBC reports.
Flags are flying at half mast and security in Nairobi is visibly tighter.