New York (CNN) -- The exasperated and infuriated mothers of the three U.S. hikers seized by Iranian forces along the Iraqi border say it's time for the regime to free their children, who will be in custody for exactly a year this Saturday.
"This is unbelievable to us at this point," Nora Shourd told CNN on Friday. "I mean, it is outrageous that they are still there."
The three mothers were interviewed on CNN's American Morning.
Shourd, the mother of hiker Sarah Shourd, said at first they thought the ordeal would be "over fairly quickly." She said it has gone on "long enough."
"Here we are at a year. You know, there's no crime committed by these three. No reason to hold them. There never has been a reason to hold them. We know it is totally political. We know they are being used for political gain," Shourd said.
Shourd said her daughter has been in solitary confinement for the year, alone 23 hours a day, and she has medical issues.
"She's not really receiving the medical care that she should. She has had one doctor's visit," Shourd said.
The remarks come ahead of a weekend of demonstrations marking the first anniversary of the jailings. On Friday, there will be protests outside Iran's embassy in London, England and Iran's permanent U.N. mission in New York.
There will be demonstrations on Friday in Vancouver, Canada and on Saturday in Paris, France; Washington, D.C.; Philadelphia, Pennsylvania; Houston, Texas; Eugene, Oregon; St. Paul, Minnesota, and San Francisco, California on Saturday.
The three Americans were detained after they allegedly strayed across an unmarked border while hiking in Iraq's Kurdistan region. The Nation magazine reported last month that two witnesses have said they saw members of Iran's national police force cross into Iraq to apprehend the three.
Tehran has claimed the three hikers are spies. Iran's intelligence minister has hinted the country may consider releasing them in exchange for the release of Iranian prisoners, according to state media.
Cindy Hickey, the mother of hiker Shane Bauer, said the families "have been more than patient and respectful."
"It is time for them to be returned. We heard over and over again that they would be granted maximum leniency. Things would move forward and nothing has happened. We need movement."
The United States and Iran have no diplomatic relations and have long been adversaries. The Pakistanis represent Iranian interests in Washington and the Swiss government represents U.S. interests in Iran.
Hickey said Swiss government officials and the hikers' lawyers have not been able to see the three.
"We heard nothing from our children. Again, one phone call, one visit. No letters. They have written letters. We haven't gotten them," Hickey said.
Laura Fattal, mother of hiker Josh Fattal, said "every day" they hope that Iran will understand "enough is enough."
It's time, she said, "for these kids to get out of Tehran and come home to the United States."
The mothers were permitted to visit their children in Tehran last May, and Fattal said the hardest day of the mothers' lives was "seeing them go into an elevator and us go into another elevator."
"We know the American government is working to end this. I know they see this anniversary as a very, very unfortunate anniversary."