Manchester City are the subject of a Premier League investigation into allegations regarding the club's finances, youth player recruitment and third-party ownership.
The announcement comes just a day after the UEFA Club Financial Control Body (CFCB) confirmed it is also investigating the Premier League leaders following allegations made against the club and their owners by German publication Der Spiegel, which drew upon documents purportedly obtained by whistleblowers Football Leaks.
The articles included claims of Sheikh Mansour's City regime topping up multi-million-pound sponsorship deals with Abu Dhabi companies in order to circumvent UEFA's Financial Fair Play (FFP) rules relating to how much money owners can put into a club.
The Football Association is investigating another of the allegations that City made an illegal payment to Jadon Sancho's agent when the England winger was 14 years old and playing for Watford.
In a statement released on Friday, the Premier League said: "The Premier League has previously contacted Manchester City to request information regarding recent allegations and is in ongoing dialogue with the club.
"The league has detailed financial regulations and strong rules in the areas of academy player recruitment and third-party ownership.
"We are currently investigating these matters and will allow Manchester City every opportunity to explain the context and details surrounding them.
"We will make no further comment until this process has concluded."
City retained the EFL Cup last month and will look to extent their one-point advantage over Liverpool at the top of the Premier League when they host Watford on Saturday.
Pep Guardiola's side are also still in the hunt for the FA Cup and the Champions League, and the former Barcelona and Bayern Munich manager told reporters on Friday that he hopes for a swift resolution to the current off-field scrutiny.
"Hopefully it can finish as soon as possible and UEFA can decide what it sees," he said, speaking before the Premier League's announcement.
"I trust what the club has done because I know them. Hopefully they can solve it as soon as possible and stop with this environment."
In response to UEFA announcing its investigation, City issued a statement that read: "Manchester City welcomes the opening of a formal UEFA investigation as an opportunity to bring to an end the speculation resulting from the illegal hacking and out of context publication of City emails.
"The accusation of financial irregularities are entirely false. The club's published accounts are full and complete and a matter of legal and regulatory record."
In January, CFCB chairman and chief investigator Yves Leterme said the club faced "the heaviest punishment" of exclusion from the Champions League if the allegations that they deceived UEFA over sponsorship income were proven.
City were fined £49million for breaching FFP regulations in 2014, while UEFA warned in November that any investigation could be reopened should new information from the time of that sanction come to light.
However, Turkish Super Lig club Galatasaray last month successfully appealed to the Court of Arbitration for Sport when the CFCB sought to reinvestigate a June 2018 settlement in relation to FFP breaches.
