An £100,000 reward is being offered in exchange for information relating to the disappearance of RAF Honington serviceman Corrie McKeague.
His mother Nicola Urquhart told members of the Find Corrie group last night that Suffolk businessman Colin Davey has decided to double the substantial sum, which originally stood at £50,000.
It is hoped the move will bring fresh leads to the case in a week that saw a landfill search for the 23-year-old end.
Nicola said: 'I would fail miserably if I tried to find the words that describe how I feel about Colin's generosity.
MORE: Police end landfill search for Corrie McKeague saying they are 'content' he is not there'We can never thank him enough. I would beg anyone who has information no matter how small they think it may be to come forward.
'There may be someone out there that thought that because the police were so sure Corrie was in the landfill that their information was not important so never came forward. Please do it now.'
Corrie went missing on September 24 last year after a night out in Bury St Edmunds.
He was last seen on CCTV at 3.24am near a loading bay area behind Greggs, known as the Horseshoe.
A 20-week search of a landfill site in Milton, Cambridgeshire, was called off on July 21 after no evidence of his body was found.
However, on October 23 a fresh attempt to scour the site was launched, in an area known as cell 22 close to the site of the initial search area.
Police said earlier this week that they are content he is not in the landfill areas searched.
On hearing the news Suffolk's police and crime commissioner Tim Passmore pledged to ask the government to pay for the £1.5million search for missing RAF serviceman Corrie McKeague.
In a moving statement issued following the news, Corrie's mother Nicola added: 'The peace of mind they have given me is immeasurable.
'I will no longer picture my son in that landfill.
'I know how hard they have tried to find Corrie and we will never be able to thank them enough for their efforts.
'What I can say, is, my complete trust in Vince and his team leaves me certain that had Corrie been in that landfill, they would have found him.'
A primary hypothesis held by Suffolk police, suggesting Corrie ended up in the waste disposal, was endorsed by a review of the investigation carried out by the East Midlands Special Operations Unit.
Detective Superintendent Katie Elliott said: 'We are still committed to continuing with the inquiry.
'There are a number of other theories about what could have happened to Corrie and we are continuing to test the evidence to help us understand what happened to Corrie, which will assist in providing answers to his family.
'We feel it is important to explain to the family what we are doing, so they have the opportunity to understand and question what we have done, and why we have done it.
'We are acutely aware of the immense strain the last 15 months has placed upon Corrie's loved ones.
'We want them to be confident we are doing everything that it is practical for us to do as we strive to find Corrie.'
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