LONDON, England (CNN) -- Madeleine McCann has become an icon for missing children, her parents said Friday on the eve of the anniversary of the British toddler's disappearance from a Portuguese holiday resort.
A faded photograph of Madeleine McCann on a church notice board near where she disappeared.
"Madeleine does seem to have become iconic of missing children," Kate McCann told CNN in an interview as the couple launched a fresh appeal for information about Madeleine's whereabouts and vowed never to give up the search until she is found.
"We believe there is a very good chance Madeleine is out there," Gerry McCann said. "There is certainly no evidence to suggest otherwise and we are doing our best to find her. At the moment we've got a few pieces of a jigsaw and a huge gap and what we are trying to do is build that information."
The couple also reiterated their support for the introduction of a Europe-wide alert procedure for missing children similar to the "Amber alert" system in the United States, which advocates credit with cutting rates of child abduction.
"We are interested in making a world safer for children," Gerry McCann said. "This is something that could be implemented and it will save lives." Watch the McCanns explain how they are surviving »
Madeleine, then age 3, disappeared from the family's holiday villa at the beach resort of Praia da Luz on the evening of May 3, 2007, as her parents dined in a nearby restaurant.
Police later released sketches of a scruffy, mustachioed man who witnesses claimed to have seen carrying a young girl matching Madeleine's description.
"The chances of Madeleine being found are at least as good if not better than in those first few days," Kate McCann said. "We know she's been abducted by a man. Other than that we just don't know anything. There's a whole range of scenarios in which she could still be alive."
Since September the McCanns themselves have been considered formal suspects -- or "arguidos" -- under Portuguese law in the investigation into Madeleine's disappearance.
The couple was stunned and dismayed by the development, Kate McCann said.
"Our reaction was disbelief, first of all, and then devastation because suddenly they were looking at us -- and if they were looking at us then who was looking for Madeleine? Who was looking for my little girl? It was devastating," she said.
The couple's naming as formal suspects prompted a hostile backlash in some British newspapers. Gerry McCann reiterated that they have never been accused of having any involvement in their daughter's apparent abduction.
"Anyone can smear you and anyone can be smeared," he said. "But we have never been accused of anything and we are trying to look forward. What we are saying is that Madeleine is out there and we want to find her."
The couple, from Rothley, Leicestershire, describe the night of Madeleine's disappearance as a parent's "worst nightmare" and the "most horrific situation imaginable." Watch how the McCanns kept Madeleine in the spotlight »
"Every parent can imagine it but they will probably never feel that desperation," said Gerry McCann. "Any parent knows that fleeting feeling in a park or in a supermarket: Where's my child? And then there's that terrible realization."
The McCanns say they are now trying to lead an "ordinary family life" amid the campaign to find Madeleine, and say their 3-year-old twins' routine of swimming lessons and nursery classes has proved a welcome distraction from the search.
The pair are still too young to comprehend their sister's disappearance and still include her in their games, Kate McCann says.
"They do lots of role playing with toys in which they still include Madeleine," said Kate McCann. "If she walked through the door, I think they would be like: 'Madeleine's back, let's go to the park!'"
But the couple admit that a normal life is impossible while Madeleine remains missing.
"The concept of saying, let's go out and have a nice meal even a year down the line that doesn't hold any appeal or enjoyment," said Gerry McCann. "We need to know everything and we will never give up."
"You have moments when you are exhausted and you think you can't do this anymore but it's a second, a moment," Kate McCann said. "Because you never give up. Who would give up on their own child?" E-mail to a friend