Ayman al-Zawahiri said Barack Obama was not welcome in Egypt
A message attributed to the deputy leader of al-Qaeda has denounced Barack Obama as a "criminal" on the eve of the US president's Middle East trip.
Ayman al-Zawahiri said Mr Obama's "bloody messages" would not be concealed by "polished words".
The US president is due to make a major speech on relations with the Muslim world in Egypt later this week.
The authenticity of the audio message, posted on a website linked to al-Qaeda, could not immediately be confirmed.
The Egyptian-born Ayman al-Zawahiri is often referred to as Osama Bin Laden's right-hand man and al-Qaeda's chief ideologue.
The al-Qaeda number two said Mr Obama would not be welcome in Egypt, and referred to US campaigns in Iraq and Afghanistan.
Mr Obama's "bloody messages have been received and are still being received and they will not be covered by public relations campaigns or theatrical visits or polished words", he said.
He called Mr Obama "that criminal who came seeking, with deception, to obtain what he failed to achieve on the ground after the mujahideen ruined the project of the Crusader America in Iraq, Afghanistan, and Somalia".
He also said the Egyptian officials who will welcome the American leader are "slaves" who have turned Egypt into an "international station of torture in America's war on Islam".
Ahead of his trip to the Middle East and Europe, Mr Obama told the BBC that he wanted to "open a dialogue" between the West and the Muslim world to overcome what he said were "misapprehensions" on both sides.
He will travel to Egypt on Thursday, where he will make a speech at Cairo University.
In the audience will be 10 senior figures from the banned Islamist group the Muslim Brotherhood, the BBC's Christian Fraser reports from Cairo.
They welcome the president's visit to Egypt as long as he takes a firm stance on the Israel-Palestinian issue and works to build ties with the Muslim world, our correspondent adds.