"Brother Leader was ruthlessly killed by rebels armed by Nato forces, who invaded Libya because of its natural resources," ANCYL spokesperson Floyd Shivambu said in a statement.
The statement came after pictures of Gaddafi covered in blood were broadcast globally on Thursday.
He was reportedly shot dead near Sirte in Libya while hiding in a concrete pipe.
Shivambu said Gaddafi had resisted imperialist domination of the African continent and never agreed to the draining of natural resources from Africa, appreciating that they should be used to benefit the people of Africa.
The fact that he was killed in combat was an "inspiration to many freedom fighters across the continent and the world", Shivambu said.
"Like Colonel Gaddafi, as economic freedom fighters we will fight to the bitter end and [are] ready to pay the highest price for the retaining of South Africa and Africa’s natural resources to the rightful owners," he said.
The league was ready to fight to protect and defend the sovereignty of "our countries", to defend political freedom and de-colonisation.
Shivambu said the struggle for economic freedom and liberation would never be easy, because imperialist agents would infiltrate the oppressed and exploited people and portray anti-imperialist fighters as enemies of the people.
The struggle for economic freedom would not be easy and there would be betrayals like that of Gaddafi.
The only appropriate send off for Gaddafi was to recommit to the struggle for total economic freedom "in our lifetime" said Shivambu
"The question we should ask is who is next? Rest in Peace Brother Leader!"