Security concerns sparked by anti-government rallies in mostly-Sunni areas of Iraq in recent weeks could hamper provincial polls due in April, a top election official said on Wednesday.

Muqdad al-Sharifi, the chief electoral officer of Iraq's Independent High Electoral Commission (IHEC), also told reporters that 131 candidates had been barred from the April 20 vote due to their ties to the Baath Party of now-executed dictator Saddam Hussein.

"We have a problem in some provinces where there is a political crisis," Sharifi said, referring to weeks of demonstrations in north and west Iraq against the alleged targeting of the Sunni community by the country's Shiite-led authorities.

"The commission is worried about the continuation of this situation ... because it will create problems for the elections," he said in Baghdad at a joint news conference with UN special envoy Martin Kobler.

Sharifi said IHEC staff in Iraq's north and west had been sent threatening letters warning them against taking part in the polls.

Kobler too said the protests were "of increasing concern".

"I do hope that the demonstrations going on do not impact on the elections," he said.

Sharifi also said that of a total of 8,224 candidates who had registered to run in the elections, 131 had been barred by a commission charged with filtering out those with ties to Saddam's Baath Party.

The issue of so-called de-Baathification was extremely controversial during Iraq's 2010 parliamentary elections, the country's last set of polls, because those barred accused the commission of disproportionately targeting Sunnis.

The provincial elections come amid a political crisis in Iraq that has pitted Prime Minister Nuri al-Maliki against several of his erstwhile government partners and tensions have been heightened by the protests.