Portuguese police have acknowledged for the first time that missing four-year-old Madeleine McCann could be dead.

Chief Inspector Olegario Sousa told the BBC that new evidence had given "intensity" to the possibility that she was killed.

He said that there had been developments over the past few days that could point to the possible death of Madeleine but that there were still many lines of inquiry open.

He stressed however that neither Kate or Gerry McCann are being viewed as suspects.

Evidence uncovered this week by British sniffer dogs found specks of blood in the family's apartment bedroom.

The McCanns made emotional pleas for people to keep looking and praying for Madeleine at a church service in the Algarve resort where she vanished on May 3.

Scores of holidaymakers and locals, many dressed in green and yellow to symbolise hope, kissed the couple and shook their hands to show their support during the hour-long service.

Mrs McCann asked the people of Praia da Luz to stay with her and her husband as they continued their "journey of hope" for their "precious" daughter.

The church of Nossa Senhora da Luz was packed with people wanting to show their backing for the McCanns, who have endured one of the most difficult weeks since Madeleine went missing.

During the service today both the McCanns pointedly thanked locals for their support over the months of their ordeal.

Father Haynes Hubbard, the Anglican chaplain of the Algarve, who led the service, said those in church did not agree "for one second" that they should return home.

He went on: "Those of you who live in Luz and live around Luz, whose lives have been affected by this, will join me to say thank you to Kate and Gerry for staying here and allowing us to be part of this struggle with them. "It would be easier for us if they left, but it wouldn't be right."

The service - themed as "100 Days of Hope" - including bidding prayers for Madeleine and other missing children as well as short addresses by both the McCanns.

Her voice breaking with emotion and clutching Madeleine's favourite soft toy, Cuddle Cat, Mrs McCann said: "I would like to welcome you all here today to join us in some special prayers for Madeleine and all children who suffer around the world at this moment.

"As you are aware it is 100 days now since our little girl was taken from us.

"Every day feels so hard without Madeleine. "I could talk all day about how wonderful, how precious Madeleine is, but suffice to say we all miss her so much and our lives aren't complete without Madeleine."

Meanwhile, friends and family held a quiet vigil for her back in the UK. About 50 people gathered at the Sacred Heart Church in Rothley to say prayers and light candles for Madeleine.

Her great uncle, Brian Kennedy, said: "It was a low-key service, which is exactly what we wanted and I think it was very much appreciated."

Mr Kennedy said he hoped today would also mark an end to the high level of media attention focused on Madeleine's parents.

He added: "It's been a very hectic up and down time. I do hope they won't continue to be subject to the same intense barrage of publicity after this weekend because I think they need a bit of quiet time.

"I know they will continue with their efforts for missing children in general, as well as Madeleine."