London's Air Ambulance Charity has called on the government for urgent financial support in the spring budget.

The money would help with the charity's 'Up Against Time' campaign, which aims to raise £15 million to replace its two current helicopters by September 2024.

Despite fundraising efforts and public backing, the initiative is falling short of its projected funding target.

The charity's appeal to the government is for financial support for 25 per cent of the helicopter costs, which equates to more than £3 million.

The charity has had numerous discussions with government officials over the recent months, involving people like Sir Iain Duncan Smith MP, but have not yet had a positive response.

While the charity's current helicopters remain operational, their lifespan is nearing its end, and they are becoming harder to maintain.

Maintenance challenges have already threatened the service's availability earlier this year.

READ MORE: London Air Ambulance saved British Airways cabin crew member's life

The spring budget on Wednesday, March 6 is likely to be the last major fiscal event before the next general election.

The chancellor looks set to unveil a 2 per cent cut to national insurance to 'woo' voters.

London's Air Ambulance provide vital life-saving services to the 10 million people who live, visit and work in the capital.

The service receives 96 per cent of its funding from public donations.

Since its service began in 1989, the charity has provided critical medical assistance to more than 46,000 people in the capital, operating around the clock all year long.

London's Air Ambulance Charity is also a world leader in pre-hospital medicine, helping to shape pre-hospital trauma care both in the UK and internationally.