Subway aims to have 3,000 shops across Britain and Ireland by 2020. Getty Images

Fast food giant Subway has unveiled plans to open 500 stores across Britain and Ireland, amid an expansion drive that could create 5,000 new jobs.

The US company, which also plans to launch a new online ordering system within a year, said it aims to take the number of stores across Britain and Ireland to 3,000 over the next three years.

The world's largest fast food company currently has 2,313 restaurants in Britain and 173 in Ireland and its expansion plans would bring the tally to almost double that of its high street rival Greggs, which has 1,698 stores.

"The growth expansion has been continual," said Subway's UK director Peter Dowding.

"What we have achieved over the last few years has been phenomenal for the brand and for our franchisees across the UK and Ireland.

"We set some very ambitious targets in 2012, where we said we would get 3,000 stores by 2020 and we are well on our way to achieving that.

"In fact, we will be opening our 2,500th store, which is a fantastic achievement for the brand in the UK. It strengthens our position in the market as being the leading quick service chain in the UK."

While Subway overtook McDonald as the world's biggest fast food franchise six years ago, Dowding warned the fellow industry giant was far from being its only rival in the market.

"It's everyone. It's a very competitive world out there," he added.

In the UK, three in five Subway stores are located on the high street but the firm was yet to experience any decline in demand, despite the post-Brexit squeeze on households' budgets.

"It's business as usual," explained Dowding.

"Like any other business we're waiting to see what the government does and will tackle it from there

Subway was founded in 1965 in the US and now operates 44,000 stores, all of which are independently owned and operated as franchises of the US, across 112 countries. The chain's offering has evolved in line with the consumers' eating habits and Subway will soon overhaul its breakfast and evening menus.

"We already have a breakfast menu, but it's a part of the day we need to work on," said Dowding.

"We offer a broad range of products. We cater for choice driven by consumer demand."

Fast food's reputation for being unhealthy was a "misconception", he added, pointing out Subway's offering also includes salads and that the six-inch version of six of the nine sandwiches on offer on its menu contain less than 400 calories,