The British laboratory testing blood samples from the site of Madeleine McCann's disappearance last night said work was still "ongoing" amid reports that "significant new information" uncovered by the experts had been passed on to police in Portugal.

Scientists at the Forensic Science Service (FSS) have been carrying out forensic analysis of the blood which was recovered from the Portuguese apartment where the four-year-old went missing.

An FSS spokeswoman said: "There has been a lot of speculation. The tests are ongoing. There has been no change in that despite what the reports say."

The statement was issued last night after friends of Gerry and Kate McCann accused Portuguese police of failing to tell the couple about developments discovered by the lab.

Experts at FSS, a government-owned company which undertakes forensic analysis for police forces across England and Wales, have spent the past month analysing samples taken from the McCanns' holiday apartment in the Algarve resort of Praia da Luz.

The evidence recovered from the flat includes blood flecks found by British sniffer dogs on the wall in Madeleine's bedroom, where she vanished on May 3.

A London-based newspaper reported yesterday that the FSS tests had produced findings which were "likely to trigger action" - possibly including arrests - within days.

Police in Portugal would not officially confirm this, but a source said information from the laboratory had been "regularly fed back" to detectives.

Chief Inspector Olegario Sousa, spokesman for Portugal's Policia Judiciaria (PJ), which is leading the investigation, said: "The information is that the results haven't arrived yet, but it might be they arrived during the day."

Mr Sousa added that all lines of inquiry were still being pursued, but the theory that Madeleine is dead is now being given "special attention".

The FSS spokeswoman added: "It's a live investigation and we are working with the police. That (the report) has not come from us."

The FSS and Leicestershire Police are working very closely on the case, often liaising on a daily basis.

A source linked to the investigation said any developments made by the FSS were immediately passed to police, who would then communicate it to PJ investigators. "Information has been regularly fed back as to the progress and where the investigation is up to," the source said.

"Information is always being fed back which Leicestershire police then pass on to the Portuguese authorities. The Portuguese are leading on the investigation and they have to be the ones to act on any information.

"On any important case, as soon as any progress is made the information is passed on. On something so important, any information would not be sat on. It is always being fed back."