Manchester United
Manchester United have been the biggest spenders in the Premier League this seasonReuters

English Premier League sides have spent a record £965 million in the summer and winter transfer windows this season, revealed a research conducted by business advisory firm Deloitte.

Although the Premier League sides' expenditure of £130 million in January is nowhere near the record of £225 million set in January 2011, the combined costs of the summer and winter transfer windows have easily smashed last season's record of £760 million.

Dan Jones, a partner in the Sports Business Group at Deloitte, says that the "revenue growth at Premier League clubs" have enabled them to spend more money on transfers this season.

"Despite the relative restraint we have seen in the January window, 2014-15 is still a record season for Premier League spending," he said.

"Last season saw Premier League spending surpass the £700 million threshold for the first time, and the revenue growth at Premier League clubs is such that they have been able to record a combined transfer spend this season of over £950 million."

Manchester United alone spent a whopping £153 million on the transfer of players including Angel Di Maria, Ander Herrera, Luke Shaw and Marcos Rojo in the summer, where the total expenditure for Premier League sides shot to a record £835 million, £205 million more than that of last season.

Dan Jones, a partner in the Sports Business Group at Deloitte, says that he is not entirely surprised to see EPL sides set a new spending record this season, although he admits he was expecting "more major deals" to take place in January.

"Given the record level of spending seen in the summer, it is not entirely surprising that we haven't seen a new record for the January window," said Jones. "However, with all Premier League clubs recording record revenues, we might have expected one or two more major deals in this window."

The research further revealed that EPL clubs have now spent in excess of £1.3 billion in the last 13 winter transfer windows between 2003 and 2015.

Serie A clubs are the second highest spenders in the January transfer window with a reported total of £65 million, followed by sides in the Bundesliga and the La Liga, who had a reported aggregate of £52 million each.