A car bomb in central Baghdad has killed at least three Shi'ite pilgrims, police and medics said.
Iraq's majority Shi'ites are preparing for the religious festival of Ashura, an event that has been marred by car and suicide bombings in the past.
A third car bomb in the Iraqi capital Baghdad has killed 15 people and wounded 44, according to the Reuters news agency.
Two previous car bombs in Shi'ite parts of the city killed a total of 19 people and wounded another 45.
Officials in Iraq have said that 17 people were killed in two car bombs in the capital Baghdad, the Associated Press reports.
The blasts reportedly took place in Sh'it areas of the city.
Update: The Reuters news agency out the death toll at 19 citing Iraqi security and medical officials.
At least 27 people have been killed in a series of bombings across Baghdad today, including three which were detonated in just 10 minutes.
The attacks are among the most significant in Baghdad since insurgents led by the Islamic State extremist group captured Iraq's second-largest city Mosul last month at the start of its blitz across Iraq.
Today's deadliest bombing took place in the Shiite neighbourhood of Abu Dashir, where a suicide attacker rammed a car packed with explosives into a checkpoint, killing at least nine people and injuring 19, officials said.
Four policemen were among the dead, a police officer said.
There are conflicting reports as to who is prevailing in the fighting in Baquba - the Isis extremists or the government - but it is very close to Baghdad: less than 40 miles away.
I have seen more soldiers on the streets of Baghdad today than there usually are, and they are carrying heavier weaponry than they usually do.
Amongst the ordinary population we have had some reports of panic-buying, people stockpiling food and water, and supermarkets running out of stock.
Tragically, this is a city well used to terrorism. Today, there was a roadside bomb in the centre of Baghdad which killed three people.
The population is now once again getting used to the prospect of Baghdad becoming a full-on war zone. It is a frightening possibility for them.
Defence secretary Philip Hammond has said that the UK will be "putting a small team" in the British Baghdad embassy, to increase awareness and help plan for possible emergency situations.
Mr Hammond also said that the British government will only give "technical advice" to Iraq at this stage, which will be delivered through either military or civilian methods.
The statement comes after increased sectarian violence in the north of Iraq by Islamic militants.
The US State Department said it is increasing security at its embassy in Baghdad and will move some workers out of the Iraqi capital - but said a "substantial majority" of the embassy presence will remain.
"Some additional U.S. government security personnel will be added to the staff in Baghdad; other staff will be temporarily relocated - both to our Consulate Generals in Basra and Arbil and to the Iraq Support Unit in Amman," a State Department statement spokesperson said.
Americans are being evacuated from an airbase near Baghdad to escape the incursion from Islamist group ISIS.
Officials said three planes were set to leave Balad airfield in Sunni Muslim territory north of Baghdad, with ISIS militants sweeping south after capturing the city of Mosul yesterday.
Those being evacuated including 12 US service personnel and several hundred contractors, the Associated Press reports.
These dramatic photographs capture the explosion seen during a car bomb attack at a Shi'ite political organisation's rally in Baghdad.
The series of explosions killed 18 people, police and medical sources said.
Three bombs exploded in succession as people were leaving the rally, Reuters reporters at the scene said.
19 people have died after two bomb attacks targeted a commercial street and market in the same neighbourhood of northern Baghdad.
The attacked happened when a car bomb exploded in a commercial street in Azamiyah, killing 12 people and wounding 28, police said.
Minutes later a second bomb exploded near a market, killing seven and wounding 27.