Men survey a shop damaged by a suicide attack in Kabul on Tuesday. (Lucy Nicholson/Reuters)

Millions of Afghans have not been deterred from registering to vote despite a hike in the number of insurgent attacks in days leading up to the Afghanistan election, an ISAF spokesman said on Tuesday.

Canadian Brig-Gen. Eric Tremblay said insurgent attacks have averaged 32 a day in the last 10 days, but increased to 48 attacks a day within the last four days.

Despite the increase, Tremblay said the insurgents "do not have the capacity to intimidate and prevent 50 million Afghan voters who have registered for this election."

Tremblay noted that with 6,500 potential polling stations, the insurgents, based on the number of average attacks they are launching, "aren't going to able to attack even one per cent of the entire polling sites in the country."

Meanwhile, officials said the NATO-led International Security Assistance Force will stop all offensive operations on Thursday to focus its efforts on maintaining security for the presidential election as more attacks rocked the capital Kabul.

The order to halt operations followed a similar order issued to Afghan forces by Afghan President Hamid Karzai, who called for an election-day truce.

"Only those operations that are deemed necessary to protect the population will be conducted on that day," ISAF said in a statement issued Tuesday.

Canadian forces in Afghanistan will "continue to do everything we can to protect Afghan citizens, to preserve the integrity of the election, to allow them and enable them to vote," said Defence Minister Peter MacKay.

But providing the security for the vote is proving to be an "enormous challenge," MacKay said.

Attacks ahead of vote

Attacks ahead of the election continued on Tuesday as two mortar rounds struck near the presidential palace in Kabul and a suicide bomb detonated on a major road leading into the capital.

The suicide attack on a NATO convoy headed toward a British military base killed at least seven people and wounded about 50 people, officials said.

Two UN staff members were killed and a third was wounded, according to officials.

NATO confirmed that some of its troops were wounded in the incident but none died.

Most of the dead were shopkeepers on Jalalabad Road, said CBC correspondent Susan Ormiston, who was travelling on the road when the blast occurred.

The blast destroyed about 12 vehicles near the bombing site and damaged several surrounding buildings, according to witnesses.

Meanwhile, a suicide bombing also struck the gates of an Afghan army base in the southern province of Uruzgan on Tuesday, killing three Afghan soldiers and two civilians, according to police.

Afghan policemen keep watch in Kabul on Tuesday. (Ahmad Masood/Reuters)There were no reports of injuries or major damage at the presidential palace.

Taliban threaten voters

The Taliban have threatened to disrupt polls as Afghans vote on Thursday for their president and provincial councils.

More than 100,000 international troops will be stationed around the country to help protect civilians while they cast their ballots.

But in an effort to ensure there is not the perception foreign forces are running the election, a 175,000-member force made up of troops from the Afghan National Army and specially trained police officers will be taking the lead in protecting polling stations and the roads leading to them.

The issue of security has been top of mind for many Afghan voters, said Grant Kippen, a Canadian who is serving as head of the Afghan election complaints commission. But Kippen said he gets the sense from many citizens that they still intend to vote on Thursday.

A low voter turnout could put the legitimacy of the results into question, according to analysts.

There have been concerns election tensions could manifest themselves in street violence and allegations of fraud.

The election complaints commission is investigating reports that thousands of voter registration cards are being sought and bought by warlords, Kippen said.

Polling station staff have been trained to spot the fakes and "they'll be doing everything in their ability to prevent it," he said.

Meanwhile, some of the opposition candidates allege Karzai is using state resources to ensure re-election.

Karzai leading, according to poll

Election campaigning officially ended just after midnight on Tuesday.

According to the United Nations, there are 41 presidential candidates and more than 3,000 people running for provincial council seats.

Karzai and his main rival, former foreign minister Abdullah Abdullah, have made a final push and held several rallies.

Karzai won the 2004 presidential election with 55 per cent of the vote and is widely considered to be the front-runner for the Aug. 20 vote.

A candidate needs 50 per cent of the vote to avoid going to a run-off election for the top two finishers.

But a U.S. government-funded poll released earlier last week suggests the election will likely be sent into a run-off vote with Karzai garnering 36 per cent of the vote and Abdullah 20 per cent.

Analysts have said that if the election goes to a run-off vote, Karzai could be vulnerable if his opponents rally around an alternative candidate.

With files from The Associated Press