TELECOM giant EE has unveiled a £1.5bn investment plan to improve its rural coverage and expand its 4G service.

The three-year Rural Investment programme aims to improve coverage for both voice and data services to 90% of the UK geography with 99.6% reliability.

Investment in innovation and new technology was key to EE's ambition to connect every home in the UK and minimise coverage 'not spots', said the company.

At the same time, EE aims to deliver superfast 4G to more than 99% of the population, with highest capacity 4G+ in 20 of the busiest UK cities by 2017.

EE chief executive Olaf Swantee said the investment would focus on rural areas while continuing to increase speeds and capacity with "deeper coverage" in more cities.

Mr Swantee said: "We're announcing the next stage with a commitment to, once again, radically improve mobile coverage, this time with a strong focus on rural UK."

Smart devices – including smart phones and tablets – were playing an ever-increasing part in customers' lives in every part of the UK, said Mr Swantee.

EE's rural network reach would be expanded by more than 1,500 square miles – an area bigger than the Lake District and Peak District National Parks combined.

In reports from Ofcom, EE was recently named as best for rural phone call quality and reliability, and best for 4G and 3G speeds and coverage, said the company.

A recent national report with more than one millions samples ranked EE as the UK's number one network, including being number one for call and data.

But customers continue to report poor EE coverage in some rural areas.

The company's Signalling the Future manifesto also outlines policy priorities for the next government to help accelerate the rollout of digital infrastructure in the UK.