Eight people died, including a NATO soldier, and 55 were wounded in the two attacks, authorities said. In eastern Afghanistan, two U.S. service members were killed and three wounded in a separate bombing, the U.S. military announced, pushing the death toll this month for the American force to 26.
The latest attacks were an ominous sign that the Taliban and their allies are determined to disrupt Thursday's election, in which incumbent Hamid Karzai is up against some three dozen other presidential candidates. The Islamist insurgents have threatened those who take part in the election - a crucial step in President Barack Obama's campaign to turn around the deteriorating war.
U.S. officials believe a strong turnout is essential if the new Afghan president is to gain the legitimacy to tackle the formidable challenges facing this nation, including the insurgency, political divisions, ethnic tension, unemployment and corruption.
In a bid to promote a big voter turnout, the NATO-led military force announced that the more than 100,000 international troops here will refrain from offensive operations on election day, focusing instead on protecting voters.
"Our efforts alongside our Afghan security partners will focus on protecting the people of Afghanistan from the insurgents so that the population can freely exercise their right to choose their next president and their provincial representatives," NATO spokesman Brig. Gen. Eric Tremblay said.
Fearing that violence may dampen turnout, the Foreign Ministry issued a statement Tuesday asking news organizations to avoid "broadcasting any incidence of violence" between 6 a.m. and 8 p.m. on election day "to ensure the wide participation of the Afghan people." The statement did not spell out any penalties for those that do not comply.
The English version said media "are requested" to follow the guidelines. The version in the Afghan language Dari said broadcasting news or video from "terrorist attack" was "strictly forbidden."
It was unclear how the government intended to enforce the ban. Rachel Reid, the Afghanistan researcher for Human Rights Watch, said freedom of expression was enshrined in the Afghan constitution and that any attempt to censor the reporting would be "an unreasonable violation of press freedoms."
"Afghans have a right to know about the security threats that they face, and make their own assessments about security," Reid said.
Despite heightened security in Kabul and other major cities, a series of attacks in the capital, starting with a suicide bombing Saturday that killed seven people near the main gate of NATO headquarters, has raised doubts that Afghan authorities can guarantee security on election day.
In the Tuesday suicide attack, the bomber detonated an explosives-laden vehicle as a NATO convoy traveled along a major highway near a British military base on the eastern outskirts of Kabul. The alliance did not specify the nationality of the NATO soldier who was killed.
Two Afghans working for the U.N. were also killed and one was wounded, the U.N. mission here announced.
In a statement issued in New York, U.N. Secretary-General Ban Ki-moon said he was "deeply distressed" by news of the attack.
Zabiullah Mujahid, a Taliban spokesman, claimed responsibility for the blast in a telephone conversation with The Associated Press. He said the attack was "part of our routine operations" and not directly linked to the election.
British troops guarded the blast site as rescuers rushed the wounded to hospitals. An AP reporter saw British soldiers collecting what appeared to be body parts from the roof of an Afghan home. He also reported shouting matches between British troops and Afghan security personnel at the blast site.
About a dozen private vehicles were destroyed along the road. People used their hands to dig through the rubble of a damaged building searching for survivors. Families carried the wounded away from the scene.
Hours before the suicide attack, militants fired a pair of rockets at the presidential compound in central Kabul. At least one round landed in the palace grounds but caused no casualties, Karzai's spokesman Humayun Hamidzada said.
Karzai is favored to finish first in the Thursday ballot, although a late surge by former foreign minister Abdullah Abdullah has raised speculation about a possible runoff if the incumbent fails to win more than 50 percent of the votes. Recent polls show Karzai ahead but several percentage points shy of the 50 percent mark.
Elsewhere, a suicide bomber struck the gates of an Afghan army base in the southern province of Uruzgan, killing three Afghan soldiers and two civilians, provincial police chief Juma Gul Himat said.
