Iraq is to close all its land borders for three days around the 30 January elections in an attempt to boost security, election officials have said.
Suicide attacks are now almost a daily occurrence in Iraq
Only vehicles with official permits will be allowed on the roads over the same period, in an attempt to prevent car bombings.
Car bombs driven by suicide attackers have become a feature of the insurgency against US-backed authorities.
Tuesday saw an attack on the offices of a Shia Muslim political party.
In a separate gun attack, an election candidate was killed, while militants threatened to kill eight Chinese hostages within 48 hours.
However, kidnappers in the northern city of Mosul freed a Catholic Archbishop a day after he was abducted.
The Iraqi Interior Minister, Falah Hassan al-Naqib, has warned that the country risks sliding into civil war if the Sunni Muslim minority boycotts the elections later this month.
The Iraqi diaspora is preparing to vote across the world
Sunni clerics have called for a boycott of the vote and Sunni insurgents have threatened to attack polling stations during the elections for a transitional national assembly on 30 January.
Shia Iraqis - who make up some 60% of the population - believe they will win the election by force of numbers, says the BBC's Jim Muir in Baghdad.
The interim Iraqi authorities announced the draconian security measures to try to ensure as much security as possible for the poll, our correspondent says.
Efforts will be made to close all land borders from 29-31 January to prevent foreign fighters entering Iraq to join the insurgency. Only pilgrims returning from the Hajj in Saudi Arabia will be allowed to cross.
However, policing long, porous stretches of the frontier has not proved easy in the past.
All three days around the polls have been declared public holidays, so shops and offices will be shut
Existing curfews will also be extended.
Overseas voting registration began on Monday, and already more than 18,000 Iraqis in 14 countries have successfully registered.
The election candidate who was killed was gunned down in the southern city of Basra. He was allied to interim Iraqi Prime Minister Iyad Allawi.
The Supreme Council for the Islamic Revolution in Iraq (Sciri) said it was targeted in a Baghdad suicide bombing that killed at least two people and injured two more.
The Shia party is expected to do well in the elections.
Body parts and wreckage littered the street in the Jadriyah district of Baghdad after the car exploded at a checkpoint about 25m (80ft) from the Sciri offices.
Sciri leaders have described attacks on their party as an attempt to provoke sectarian conflict.
On 27 December, a bomb attack on a Sciri office in Baghdad killed 13 people and injured 39.