A television appeal about the 2007 disappearance of British girl Madeleine McCann in Portugal has triggered nearly 1000 calls and emails, Scotland Yard said on Tuesday.
Detectives published new electronic images of men they want to trace, plus a reworked timeline of events leading up to the three-year-old's disappearance.
The appeal, based on two years of work raking over the case, was broadcast Monday on the BBC's Crimewatch programme.
"We have now had over 730 calls and 212 emails as a direct result of the specific lines of enquiry we issued," said Detective Chief Inspector Andy Redwood, who is leading the investigation.
"Detectives are now trawling through and prioritising that material. This will take time.
"We are extremely pleased with the response."
Officers are particularly keen to find one man seen carrying a young child in the popular Algarve beach resort of Praia da Luz on the night of 3 May 2007.
He was spotted around 10pm the time Kate McCann discovered her eldest daughter was missing from their holiday apartment.
Police said the man was of "vital importance" in their quest to discover what happened to Madeleine, who vanished just a few days before her fourth birthday.
The British detectives now believe an earlier sighting of a man carrying a child in pyjamas is irrelevant.
The appeal was to be repeated in the Netherlands on Tuesday, in Germany on Wednesday, and in Ireland.
Redwood is travelling to the Netherlands and Germany to appear on the broadcasts there.
But the appeal is not being screened in Portugal, although it has received media coverage there.
Crimewatch editor Joe Mather told BBC radio: "It's been a truly unprecedented response.
"There were lots of calls from British people who were in Praia da Luz around the time of Madeleine's disappearance who'd never previously spoken to the Met (Scotland Yard)."
Regarding the man police are keen to trace, he said the public came forward with "several different names but also several callers mentioned the same name for that man".
"It is a long shot but it's remarkable how often results are possible even several years down the line. There were genuinely useful calls."
The new e-fits of the man whom police are especially keen to trace were based on descriptions from an Irish family. He was seen about 500 metres away from the McCanns' apartment.
The child fitted Madeleine's description and did not seem in distress.
The witnesses described the man as white, between 20 and 40 years old, with short brown hair, of medium build and height and clean-shaven. One image shows him with a fuller jaw than the other.
Police said one theory was that the abduction could have been planned, which would have involved reconnaissance.
The McCanns had been dining with friends in a tapas restaurant about 50 metres away.
They were also interested in tracing "one or two" fair-haired men who had been seen "lurking" around the apartment complex before Madeleine's disappearance. Witnesses said the men were speaking German or Dutch.
Detectives also speculated that Madeleine may have disturbed a burglary, pointing to a sharp increase in local break-ins in the months leading up to the incident.
They were also looking at possible bogus door-to-door charity collectors operating in the area.
During Crimewatch, the McCanns who launched a global media campaign to find their daughter said they were still optimistic she could be traced.
"We're feeling hopeful," said father Gerry McCann. "These cases can get solved", he said, citing instances where long-lost people have been found.
Scotland Yard is offering a reward of up to £20 000 for information leading to the prosecution of McCann's abductor.
Portuguese authorities closed their investigation in 2008, but Scotland Yard spent two years reviewing the case at the British government's request and opened their own probe in July this year.
The operation has interviewed more than 440 people and identified 41 "persons of interest".