A government spokesman said Mr Mwanawasa was in London for a routine check-up to ensure his fitness ahead of the election campaign.
But another government source said the president became unwell ahead of a planned trip to the country's north.
No details were given on the medical condition of the 57-year-old leader.
Vernon Mwaanga, chief government spokesman, played down suggestions Mr Mwanawasa had cancelled plans because of sickness.
Mr Mwaanga said the president flew to London on his doctors' advice to get a check-up "before he gets busy with his campaign".
Mr Mwanawasa had been due to make a three-day trip to the northern Copperbelt Province.
A senior government official had told the Agence France-Presse news agency: "He became unwell just before he could fly to Copperbelt."
This article makes me think...who cares? Hes not Pope John Paul II.
What a bummer, This guy goes all the way to London for a check up. He couldnt just went local? It amazing how these people go telling their citizens "We have great hospitals" but they wont get a check up in the very hospitals they support.
Perhaps he suspected that he was afflicted with something that the hospitals there were not properly equipped to treat? Or he had another reason to go to the UK? People read way to much into the tiniest actions of a world leader. If he wants to go on vacation, and get away from the country for a while, or has friends in the UK, it would look really bad for him - skipping campaigning for an election for that. If he's out of the country for medical care, its a little harder to blame him for leaving the country during campaigning
That's the fine line in Africa. As long as political leaders continue to utilize European Healthcare and Banking Systems while their own people are left without the same choices, there is going to be a glaring double-standard that leaves people wondering, "WHY?". When I studied in West Africa, my roommate was from Botswana and had been sent to Ghana to attend Medical School. It was sponsored by the United Nation's W.H.O. program and it did a lot for to realize how many answers to African problems can be tackled by people in Africa. The problem is all the barriers that are placed between them - centuries of misuse of the land, colonizational and imperialism. A lack of solid education systems with high amounts of greed and corruption in political ranks. A devestating hole when it comes to direct foreign investment and a series of governmental failures that were underscored by Western values and attempts to use European ideas to define what the country was, who the people were and what rights they deserved. Neither side is really innocent here. We can't expect the leaders to languish in poor health care but we can't expect them not to demand better and perform better. There is so little accountability in many of these countries of the leaders to the people. It's such a quagmire, but one that I still retain hope that it will someday improve.
