Abigail Borg, the wife of Sandro Grech, who is battling a rare and aggressive form of leukaemia, has accused an air ambulance company of blackmail after her husband's long-awaited journey to China for treatment was abruptly delayed.

In a Facebook post on Tuesday, Borg said that today was supposed to be the day Sandro would finally begin his journey to China for the treatment he so desperately needs to survive.

"Instead, the plane never even took off to collect us. This delay is not our fault. It is entirely the consequence of the actions of the air ambulance company," Borg said.

She said that after the family had already paid everything, the air ambulance company demanded a further €80,000 and tried to force her to sign conditions that made no sense, including making public statements that do not reflect the truth.

"They wanted me to give up my legal rights to recover the money that had been overpaid. This is the Maltese people's money. This is nothing but blackmail," Borg said.

She said the family were even willing to pay more just to ensure that Sandro could leave on Tuesday but said that they "will never allow anyone to steal from us our right to justice."

"They even went so far as to attack our Commissioner in London for being there to help a Maltese citizen in difficulty," Borg added.

She said that the family's lawyers have already informed them that the family are holding them personally responsible for every hour of delay and for every risk Sandro is facing because of their tactics.

"We will never give up. We are working every minute, day and night, with the authorities to find another way for Sandro. I am certain, and I say this with my head held high, that the Maltese authorities will never bow to the threats of this company. When the Maltese people unite as one, nothing can stop us from achieving what is right," Borg said.

She said that the family is receiving countless messages of support, love and encouragement, for which they are deeply grateful.

"The help from the government has never stopped, and my lawyers and friends, Aron Mifsud Bonnici and Roselyn Borg, have continued working tirelessly day and night," Borg said.

She said that while Sandro is once again in hospital, they are working together with the Travel Abroad Unit at Mater Dei Hospital to find an air ambulance flight as soon as possible.

"We had many reasons to lose hope, but the love and courage we are receiving are truly helping us keep going. Thank you from our hearts," Borg said.

Late last year, Malta rallied around Sandro in what was widely described as a defining moment of national solidarity. In less than 24 hours, the public donated €250,000. Prime Minister Robert Abela then announced that the Government would match the donations with a further €250,000, bringing the total to €500,000 - the amount originally quoted by doctors for a clinical trial in Singapore.

The family was informed by the National University Hospital of Singapore that the true cost of treatment and hospitalisation would be far higher than initially quoted, forcing the family to abandon the Singapore option.

Through the Acute Leukemia Advocacy Network, Sandro was then accepted into a comparable CAR-T therapy trial in Beijing, China, offering him the same potentially life-saving treatment.

The combined funds from the Maltese public and the Government made it possible to secure both the treatment package and the specialised air-ambulance transfer.

It was at this critical final stage - with travel imminent - that the family was confronted with the sudden €80,000 surcharge by the air-ambulance provider.