"I am honoured to have been invited to London by the British Government and the Thatcher family to attend the funeral of Baroness Thatcher," de Klerk said in a statement on Tuesday.
Britain's former Prime Minister Thatcher died of a stroke on April 8, at the age of 87 and will be remembered at a funeral that not only de Klerk will attend on Wednesday but other high-profile guests such as Queen Elizabeth II.
De Klerk said Thatcher would be remembered as a leader whose policies and approach had a significant impact on politics throughout the world.
"She will be remembered not only as one of Britain's greatest Prime Ministers but also as a leader whose policies and approach had a significant impact on politics throughout the world."
Moreover, de Klerk said Thatcher was "a steadfast critic of apartheid" that "consistently urged" the South African government to bring constitutional change to South Africa and release Nelson Mandela.
"She had a much better grasp of the complexities and geo-strategic realities of South Africa than many of her contemporaries," he added.
'No peaceful solution'
"She realised that there would be no peaceful solution to the problems of South Africa unless the reasonable concerns of all South Africans – including whites – were taken into consideration."
De Klerk – who alongside IFP president Mangosuthu Buthelezi are the only high-ranking South African politicians that will attend her funeral – also said he was honoured to have had the former British prime minister as a friend.
Thatcher served as political leader of the United Kingdom at the height of Apartheid between 1979 and 1990.
She consistently opposed the imposing of sanctions against South Africa as punishment for implementing Apartheid.
Her role in bringing about the end of the prejudiced system of racial segregation is thus a point of debate across the political spectrum.
De Klerk said while Thatcher at no time gave the slightest support for apartheid or racial discrimination she understood how the imposition of sanctions would have prevented real transformation.
De Klerk said Thatcher's success in the warding off of sanctions thus prevented South Africa withdrawing into a grim survivalist fortress under the leadership of PW Botha.
"Margaret Thatcher's efforts to ward off comprehensive sanctions were probably her greatest contribution to the subsequent successful constitutional evolution of South Africa," he said.
"There can be no doubt that Margaret Thatcher prolonged Apartheid," ANC spokesperson Keith Khoza. "She called the ANC a terrorist organisation and even referred to our first democratically elected president Nelson Mandela as a terrorist. She did not want South Africa to be ruled by the black majority."
Khoza said de Klerk was fully within his rights to attend Thatcher's funeral but the ANC would not be sending any representatives.
"The comments that de Klerk is making now is indicative of his backward thinking. To this day he is still trying to excuse apartheid and paint it as acceptable," he added.