However, the former cabinet Minister has insisted that he is still in UDF and holding his position.
The development comes barely months after his suspension pending a disciplinary hearing on the matter.
According to UDF spokesperson Ken Ndanga , Omar was found guilty of bringing confusion in the Yellow camp.
He said the decision to boot the former Lilongwe City South West Member of Parliament from the Party was made on Friday during a National Executive Committee (NEC) meeting held at Golden Peackok Hotel in the capital Lilongwe.
The meeting was chaired by UDF party’s third vice president, Charles Chikuwo and Omar was available.
Apart from Omar popularly known as Mnthandizi, he party has also expelled two other officials namely deputy director of women, Zaituna Yusuf and deputy central region governor, Dinocius Magombo.
For some months, there have been two UDF Central Region governors, each claiming to be legitimate: Magombo and Martin Matabwa.
The group led by Magombo, which has been supporting Omar, opened a new office at Area 24 in Lilongwe in August.
But the other committee, led by Matabwa, was operating from a motel at Biwi, before recently moving to new offices along Likuni road.
However the party has said recognises Matabwa as the regional governor and Magombo as his deputy.
Both Yusuf and Magombo are also not in agreement with the decision.
In an interview Ndanga told MBC, Omar, Yusuf and Magombo have been expelled for gross misconduct.
“Honourable Omar has been expelled from the party for forming parallel structures. He was appointing new regional governors. He also opened a new regional office [in Lilongwe], without the knowledge of the party.
Apart from that, he was conducting meetings without the knowledge of the party’s secretary general,” Ndanga said.
Sources say the former Lilongwe City South West legislator, was calm after the decision was made, and even shook hands with some party officials who attended the meeting at the end.
In an interview over the weekend, Omar said he does not accept the decision and that he is still a member of UDF.
“I’m still a member of the party. I will die UDF. That is a decision made by disgruntled people. I cannot accept that. In the meeting, I challenged them to call all district governors and regional committee members to hear from them if the allegations were true but they did not accept,” he said.
Omar was elected vice to the party’s president, Atupele Muluzi, at a convention which took place in October 2012.