The summer transfer window has now begun, with rumours and speculation continuing to swirl as Manchester City eye possible reinforcements.

The 2018-19 champions did not bring in a single player during the January transfer window, despite suffering a defensive shortage for much of the 2019-20 campaign, but they have already started their business for the summer.

Here, Sports Mole rounds up the latest news on possible comings and goings at the Etihad.

Thursday morning's Manchester City transfer talk news roundup:

Kalidou Koulibaly agent 'informs Napoli of Manchester United interest'

Napoli have allegedly been informed that Manchester United remain interested in signing defender Kalidou Koulibaly.

While the centre-back has previously been regarded as indispensable at Stadio San Paolo, president Aurelio De Laurentiis is now open to parting ways with the club's key asset.

Keen to strengthen their backline before the end of the transfer window, Manchester City boss Pep Guardiola wants to bring the 29-year-old to the Etihad Stadium.

However, according to Il Mattino, Fali Ramadani has told Napoli that United are interested in negotiating a deal for the player.

Despite previously being valued in the region of £80m, the Serie A outfit may be prepared to cash in for a fee around the £60m mark.

Koulibaly still has three years remaining on his contract.

Lionel Messi 'agrees £623m deal with City Football Group'

Lionel Messi has reportedly agreed a staggering €700m (£623m) deal with City Football Group as the Argentine prepares to leave Barcelona.

The forward recently told Barca that he wants to leave the Catalan giants during this summer's transfer window, and the South American's father and agent Jorge Messi has flown to Spain for talks.

Manchester City have emerged as the favourites for the 33-year-old despite suggestions that Chelsea, Manchester United, Paris Saint-Germain and Inter Milan were also interested.

According to the Daily Record, Messi has agreed a five-year deal with the City Football Group which will see him represent City before eventually joining MLS outfit New York City FC.

The report claims that the attacker is likely to spend three seasons with the Citizens before moving to North America, although there is 'a degree of flexibility' in the deal.

Messi was not present during Barca's pre-season training session on Monday, while he also did not turn up for a coronavirus screening on Sunday as he looks for an exit.

The four-time Champions League winner has a contract at Camp Nou until next June, but he is attempting to leave on a free transfer despite a clause allowing him to depart for nothing this summer expiring in June.

More transfer news from Manchester City:

Manchester United 'line up Milan Skriniar as Dayot Upamecano alternative'
Manchester United make contact with Inter Milan to discuss a potential deal for Milan Skriniar, according to a report. Read more.

Lionel Messi's Barcelona future 'no closer to being resolved'
Jorge Messi - the father of Barcelona forward Lionel - reportedly makes no progress in discussions with club officials over the future of the Argentine. Read more.

Lionel Messi father lands in Barcelona for showdown talks
The father of Lionel Messi lands in Spain on Wednesday morning for showdown talks with Barcelona. Read more.