As many as 80,000 people could die if there was an outbreak of a drug-resistant blood infection in Britain, with numbers infected as high as 200,000.
The forecast by the National Risk Register of Civil Emergencies, which was published by the Cabinet Office, warns that much of modern surgery including routine procedures may become dangerous due to risk of infection.
Influenza pandemics would become more serious without effective treatments.
The numbers of infections complicated by antimicrobial resistance was expected to "increase markedly" over the next 20 years, the report said.
The UK government is "leading work with international partners" to tackle this "global problem".
A flu pandemic and "catastrophic terrorist attacks" have been given the highest impact ratings in the Cabinet Office document which rates threats to the UK both in terms of their anticipated likelihood and their "relative impact".
The chief medical officer for England, Dame Sally Davies, has repeatedly warned of the dangers of AMR calling it a "ticking time bomb".
She said last year: "The world simply cannot afford not to take action to tackle the alarming rise in resistance to antibiotics and other antimicrobial drugs we are witnessing at the moment."
US travellers' bug concerns
Just a couple of days ago the US Centers for Disease Control and Prevention (CDC) reported that international travellers were bringing back and spreading a drug-resistant bacteria called shigella sonnei in the US.
Dr Margaret Chan, the director general of the World Health Organization, had warned last year about the dire consequences of emerging drug resistance when she said: "Things as common as strep throat or a child's scratched knee could once again kill."
US President Obama signed an executive order to create a task force to tackle the issue of antibiotic-resistant bacteria.
Indiscriminate and improper use of antibiotics has led to the rising global health catastrophe of drug-resistant bacteria. Antibiotic use has risen by 36% globally during the last decade with India leading the pack.
According to the CDC, over two million people are infected by drug-resistant bacteria every year, and 23,000 die of related infections.
Many companies have discontinued antibiotics development due to poor returns on investment and only two new antibiotics have been approved since 2009.
Initial studies by researchers at Northeastern University in Boston recently developed a compound isolated from ordinary soil which is said to work against the growing army of superbugs, ranging from staphylococcus to drug-resistant tuberculosis. But the lab to market period is a long wait
More about antibiotic resistance