A Briton and two US nationals working in Iraq have been abducted in Baghdad.
The Iraqi Interior Ministry said gunmen seized the men at dawn from a house in the capital's Mansour neighbourhood.
US and British embassy officials confirmed the kidnappings of the men, workers for a building contracting firm based in the United Arab Emirates.
Shortly after the abductions, a loud blast hit a residential area in central Baghdad. At least one person was killed and several were injured, police said.
At least 47 people were killed on Tuesday when a car bomb exploded close to an Iraqi police station in central Baghdad.
The US embassy in Iraq named the two kidnapped Americans as Jack Hensley and Eugene Armstrong but did not give their home towns.
The Foreign Office said that the Briton's family had spoken to Foreign Secretary Jack Straw and had requested that his identity not be released.
A spokesman said: "Members of the family have spoken to the foreign secretary and he assured them that we're doing everything we can to resolve the situation."
More than 100 foreigners seized (including two Italian aid workers, pictured)
19 being held
25 killed, including (12 Nepalese)
At least 3 Americans seized: Nick Berg - civilian - beheaded; Keith Maupin - soldier - killed (unconfirmed); Thomas Hamill -civilian - escaped
One Briton kidnapped: James Brandon - journalist - released
Iraqi interior ministry spokesman Colonel Adnan Abdul Rahman said: "Two Americans and a British civilian were kidnapped from their house in the Mansour district in Baghdad on Thursday morning around 0600 (0200 GMT)."
He said the men had been bundled into a minivan and driven off. A car was missing from the house where the men were reportedly taken.
There was no fighting as the hostages were taken. No group has yet claimed responsibility.
Mr Rahman told the Associated Press news agency that the men were employed by Gulf Services Company, a Middle East-based construction firm.
Company spokesman Khaled Abbas said: "Our first and only concern is their safety and getting their safe release.
"The families are pleading for their release and we are pleading that the captors release them as soon as possible.
"We know that the US military, the UK military, the Iraqi military and the Iraqi police are all carrying out their investigations."
The Mansour district is a wealthy residential area on the river Tigris, where many multinational companies have their headquarters.
Many foreign businessmen and contractors live there if they are not staying in the heavily defended Green Zone.
Fighters waging a 17-month insurgency in Iraq have
kidnapped more than 100 foreigners in a bid to destabilise the interim government and drive foreign troops from the country.
The bloated corpse of a man, believed to be a Westerner or a Turkish national, was found outside the city of Samarra on Thursday evening, Iraqi police said.
The man is thought to have been dead for three days.
But kidnappers released a Jordanian hostage on Thursday, an official from Jordan's foreign ministry said. The man, a lorry driver, was freed after his company agreed to pull out of Iraq.
There has been a spate of deadly attacks in recent days
The official Petra news agency quoted an official as saying Turki Simer Khalifeh al-Breizat, 54, was freed and taken to the Jordanian Embassy in Baghdad.
But the latest kidnappings brings the number currently being held to 19.
It follows the abduction of two female Italian aid workers last week, and two French journalists on 20 August.
Many aid workers and other expatriate civilians pulled out of Iraq after the Italians were seized.
Those who remain here do not move about the capital or other parts of the country without careful precaution, says the BBC's Mike Donkin in Baghdad.
Militants who have seized foreigners have usually demanded the withdrawal of foreign troops from Iraq.
Britain was the main supporter of last year's US-led invasion of the country.
It is the second largest troop contributor with more than 8,000 soldiers deployed in the south.
Many civilians from many nationalities have been seized - most have been freed after successful mediation efforts.
But many others have been killed - 12 Nepali cleaners and cooks, a Turkish laundry worker, a South Korean translator, an American businessman, two Pakistanis, two Bulgarian truck drivers and an Italian journalist.
The BBC's Middle East analyst Roger Hardy says a number of groups with a variety of agendas are involved.
Some of those kidnapped come from countries which have troops in Iraq, but others do not.
The kidnappers say that anyone helping the Americans is a legitimate target.
Meanwhile, virtually unreported by the international media, the kidnapping of Iraqis for ransom has become commonplace, particularly in Baghdad.