Afghan authorities are investigating the campaign manager for the top challenger to President Hamid Karzai after a news report quoted him as saying street demonstrations will "turn bad" if his candidate loses the upcoming election, officials said Monday.

Abdullah Abdullah's campaign manager, Abdul Sattar Murad, was quoted by the United Arab Emirates-based paper The National as saying that if Karzai wins the Aug. 20 vote "there will be a big demonstration, street demonstrations, and it will turn bad. The country will land in the middle of a crisis."

Murad was also quoted as saying his team would not accept a Karzai win because Karzai can win only through "large-scale corruption."

Murad told The Associated Press on Monday that the Interior Ministry contacted him about the comments but that he told the ministry he did not say them. However, The National told the AP it had a recording of the conversation and that all quotes were accurate.

The story, which was published last week, also quoted Afghan analyst Haroun Mir as saying "people will come with Kalishnikovs" if Abdullah does not win. Mir is the co-founder of Afghanistan's Center for Research and Policy Studies and was an aide to the late Ahmad Shah Massoud, a popular Northern Alliance leader with whom Abdullah was closely associated. Mir could not be reached for comment.

Interior Minister Hanif Atmar told a news conference that authorities are investigating.

"Anybody who says something to encourage people to violence, this is a crime," Atmar said Sunday.

The Attorney General's office confirmed Monday it had forwarded the case to the prosecutor's office of the country's National Directorate of Security, said deputy attorney general Fazel Ahmad Faqiryar. Mir and the writer of the article have also been contacted.

The action by Afghan authorities could represent officials' efforts to contain any campaign flare-ups that could lead to violence in what the top U.N. official in Afghanistan has called "the most complicated elections I have seen."

It could also represent a move by Karzai's government to press the president's advantage over a campaign gaffe by his top challenger.

Abdullah called a news conference over the weekend to address Murad's statements, saying they "were not my view or the views of my supporters." He also said he believed Murad had been misquoted.

The foreign editor of The National, Michael Jabri-Pickett, said the paper believed that Murad's statement saying the Abdullah team will not accept a Karzai win was an important story.

"A copy of the recording of Mr. Murad's interview has been given to the Ministry of Interior and they have also said they are happy that the quotes are accurate," Jabri-Pickett said. "The Ministry has assured us that it has no problem with The National. It simply asked for verification of the quotes, which we have provided."

Karzai is believed to be the favorite to win a second five-year term in the country's second-ever presidential election. But Abdullah has attracted large crowds at some campaign stops, leading his supporters to believe he has a chance of winning.

If authorities arrest Murad just weeks before the vote, it could cause a serious upheaval among Abdullah's supporters in the northern Tajik community. Abdullah is half Tajik and closely associated with the ethnic group. Karzai is an ethnic Pashtun, the dominant group in the country's south and east. Pashtuns make up 40 percent of the country's 30 million people; Tajiks make up 25 percent.

There has been little tension between the groups since the 2001 U.S.-led invasion to oust the Taliban regime. But the groups fought a vicious civil war in the early 1990s.

Campaign officials have hoped the election would not stoke ethnic tensions. The Independent Election Commission, which oversees the election, requires accredited media to sign a code of conduct that says media shall: "Not broadcast and release election reports which can cause violence or tribal, linguistic, regional ethnical and religious discrimination."

Mir told The National that if the election goes to a second round — which will happen if no candidate gets more than 50 percent of the vote — the country will "polarize along ethnic lines."

"If Abdullah says, 'I don't accept the outcome of the elections,' what will happen? We will not have peaceful demonstrations in Kabul like in Tehran or elsewhere. People will come with their Kalishnikovs. Every single home in Kabul has a gun," Mir was quoted as saying.