BT Group has reported a 21% jump in adjusted profit before tax in its most recent financial quarter, sending shares up nearly 9%. 

The profit increase came as group revenue dropped 2% year-on-year to £4.9 billion during the first three months of the year. 

For the full financial year, BT's sales dropped 5% to £18.2 billion, while profit before tax grew 11%. 

BT Global Services, which has long been the company's Achilles heel in terms of financial performance, turned its first annual profit in five years, even as sales dropped 8%.

BT said this was partly due to a 7% decline in operating costs, "reflecting the impact of lower revenue and our cost transformation programmes". 

All of BT's division saw revenue shrink during the year, but all except network infrastructure unit Openreach saw operating profit increase. 

“Our focus on improving efficiency across the business will allow us to continue to deliver strong financial results whilst making these investments," said CEO Ian Livingstone in a statement. “We have a lot more to do but we are now a lot better positioned to do it.”