Iraq's Interior Minister Bayan Bakr Solagh and British Defence Secretary John Reid said separately on Sunday that their governments had no information about the hostages - who include an American, a Briton, and two Canadians.
"We have no information," Solagh told The Associated Press in Baghdad when asked about the hostages. "From the beginning, I advised foreigners not to move freely and we are always ready to protect them."
The previously unknown Swords of Righteousness Brigade, that kidnapped the activists two weeks ago, had said they would kill them by Saturday unless all prisoners were released. They had originally set last Thursday as a deadline, but extended that date.
Another three foreigners have been taken besides the four activists.
"They are all people who came to serve us, to serve our people. This is a humanitarian matter and they were subjected to the ugliest type of blackmail," Solagh said.
"They are all people who came to serve us, to serve our people. This is a humanitarian matter and they were subjected to the ugliest type of blackmai"
Iraq's interior minister
When asked about the hostages, the Briton in particular, Reid told Sky News television in London that officials were doing "everything possible to try and make sure his life is saved and that of his colleagues is protected."
"But we have no further indication of any movement as of this morning," he added.
The four members of Christian Peacemaker Teams are Norman Kember, 74, of London; Tom Fox, 54, of Clear Brook, Virginia; and Canadians James Loney, 41, and Harmeet Singh Sooden, 32.
Fighters , including al-Qaida in Iraq, have seized more than 225 people, killing at least 38.
Last month, a German archaeologist, Susanne Osthoff was kidnapped north of Baghdad.
A French citizen who worked at a Baghdad water plant was seized earlier this month shortly after he left his house in the western neighbourhood of Mansour. And the Islamic Army in Iraq claimed in a web posting to have killed an American, Ronald Schulz, last week.
Ronald Schulz, an American,
was captured and later killed
An Egyptian engineer, Ibrahim Sayed Hilali, who was abducted by armed men on Friday in Saddam Hussein's hometown of Tikrit was found dead a day later.
Three diplomats - two Algerians and an Egyptian - were kidnapped in July and killed. The group al-Qaida in Iraq, which is led by Jordanian-born Abu Musab al-Zarqawi, said it killed the men.
Shortly afterwards, the government asked foreigners not to move alone and to ask for protection.
"I hope they inform us about their moves so that we protect them," Solagh said.
Iraq was swept by a wave of kidnappings and beheadings of foreigners in 2004 and early 2005, but such attacks fell off in recent months as many Western groups have left and security precautions for those who remain have tightened.