ODM party leader Raila Odinga flew out of the country on Thursday to the United Kingdom where he is expected to deliver a lecture at the London Metropolitan University.
He left the country despite having received an invitation to attend the Mashujaa Day celebrations in Machakos.
"I will not be able to join you in Mashujaa Day celebrations today (Thursday) for I have had to travel to the United Kingdom this morning," he posted on his official Facebook page.
"I am scheduled address students, scholars, public service officials and political leaders at the London Metropolitan University tomorrow (Friday) during the opening session of the London Political Summit 2016."
The theme of the summit is 'The Place of Opposition in a Hostile Political Environment'.
It will be opened by the Vice Chancellor of London Metropolitan University Prof John Raftery.
Despite his absence during the Machakos celebrations, he said he was in solidarity with Kenyans as the country reflects on the state of the nation.
Cord co-principal Kalonzo Musyoka attended the event.