An Independent Democrats (ID) conference to be held at the weekend could turn out to be a significant event in the realignment of South African politics, Democratic Alliance (DA) leader Helen Zille said on Friday.

Zille wrote in her weekly newsletter that it would be a privilege for her to attend the conference and that she had developed "a sound mutual understanding and respect" with ID leader Patricia de Lille.

"This weekend, the ID is holding a special conference to which they have invited leaders of various opposition parties," Zille said. "It will be a privilege to attend.

"It could turn out to be a significant event in the realignment of South African politics, a turning point in the development of our democracy."

Zille said that the ID would seek support from party delegates to amend its constitution so it could take the next steps in building "a strong, value-based alternative" to the ANC.

Zille said that she realised before the 2009 elections that she and De Lille had far more in common than the issues that divided them.

"I believed our political philosophy was compatible. We both believed in the open society, we shared an analysis of the role of the State, and we agreed that it was a priority to defend the Constitution.

"I started to believe that the ID and the DA could move beyond coalition politics."

Zille said that she approached De Lille early in 2008 and proposed that the two parties merge. In return, De Lille would be the party's Premier candidate for the Western Cape in the 2009 election.

It was, however, too early for the move and "this step was not to be".

"Fortunately, we were able to win without it," Zille said.

"But, with the 2009 election behind us, we are now ready to take the next step in preparation for the 2011 local elections."