The four Swedish troops, two of whom were said to be seriously injured in Friday's explosion in Mazar-i-Sharif, were from the NATO-led ISAF, which was set up in 2001, and were part of a British provincial reconstruction team.
"Shortly after midnight local time (2100 Stockholm time) ISAF's military hospital in Kabul announced that one of the two seriously injured Swedes had died," the statement said.
"The soldier was seriously injured in a bomb attack in Mazar-i-Sharif around lunchtime, Swedish time, Friday," it said. The identity of the peacekeeper was not given.
The explosion, caused by a remote controlled bomb, happened as the truck in which the peacekeepers were travelling passed as part of a four-vehicle patrol.
It took place near the centre of the city, where a British ISAF soldier was killed in an ambush nearly a month ago.
The second Swedish soldier remains in a serious condition in the hospital, while the other two injured are being treated in a hospital in neighbouring Uzbekistan, the statement said.
ISAF, made up of more than 8,000 troops from 36 countries, has been in Afghanistan since the former hardline Taliban government was toppled in a US-led invasion in late 2001. It came under NATO command in 2003.
The British soldier killed on October 29 was shot in an ambush on his convoy near the city's famous Blue Mosque. Five other people in the convoy were hurt.
Prior to that, attacks on ISAF peacekeepers working in northern and western Afghanistan have been rare. In the past two weeks though two ISAF soldiers have been killed in and around the capital.
A Portuguese soldier was killed on the outskirts of Kabul on November 18 when a bomb struck an ISAF vehicle. He was the 56th ISAF soldier to be killed in Afghanistan.
On November 14 a German soldier was killed in twin suicide bomb blasts targeted at ISAF vehicles. Six Afghans were also killed.
Two days later three civilians were killed in the volatile southern city of Kandahar in a suicide attack on a US-Afghan military convoy.
The suicide attacks were claimed by militants loyal to the Taliban government that was toppled in November 2001 after they did not hand over Al-Qaeda leader Osama bin Laden.
ISAF troops are based mainly in Kabul and the northern and western parts of Afghanistan, helping to maintain security and working on civilian and military Provincial Reconstruction Teams (PRT).
A separate US-led coalition of nearly 20,000 troops, most of them American, is based mainly in the more volatile south and east, the focus of attacks by Taliban and other insurgents.
Plans are under way to push ISAF troops into southern Afghanistan by next year, partly taking over from the US-led coalition hunting Taliban and other Islamic militants, including Bin Laden.
A Taliban-led insurgency against the new US-backed government has been the deadliest this year with nearly 1,500 people killed, most of them militants slain in clashes with security forces.
There are about 100 troops from Sweden with ISAF. The Swedish foreign ministry said this month it wanted to double its contingent and take over the Mazar-i-Sharif PRT, currently being run by Britain, in March 2006.