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.

Tuesday morning's Manchester City transfer talk news roundup:

Barcelona 'preparing final offer for Lautaro Martinez'

Barcelona are reportedly 'preparing a final offer' for Inter Milan striker Lautaro Martinez.

The 23-year-old enjoyed an impressive 2019-20 campaign for his Italian club, finding the back of the net on 21 occasions in 49 appearances in all competitions, including five goals in six Champions League outings.

Barca have been heavily linked with the Argentina international over the last few months, although the coronavirus pandemic has had a huge impact on the Spanish club's finances.

According to Goal, Barca are lining up a final offer for the South American as they prepare for life after Luis Suarez, who has been told that he can leave the club this summer.

Suarez is believed to be a target for Juventus, but it remains to be seen whether the Italian outfit sign the experienced forward before the transfer window closes next month.

Manchester City are also said to be admirers of Martinez, who has a contract at San Siro until June 2023, as they look for a long-term Sergio Aguero replacement.

Kalidou Koulibaly agent 'in England to negotiate Manchester City move'

Kalidou Koulibaly's agent has reportedly arrived in Manchester with the view to negotiating a move to Manchester City.

The Senegal international is thought to be a leading target for the Citizens during this summer's transfer window, but Napoli are refusing to sell unless their valuation - thought to be as high as £90m - is met.

According to Corriere dello Sport, the centre-back's agent Fali Ramadani has travelled to England in the hope of securing a move for his client to the Etihad Stadium.

City have already boosted their back line ahead of next season with the signing of Nathan Ake from Bournemouth.

Head coach Pep Guardiola is still believed to be keen on at least one more defender arriving at the club before the October deadline, though, as they look to wrestle the Premier League title back from Liverpool next term.

Koulibaly, who has previously been linked with Manchester United, Barcelona and Real Madrid, still has three years left to run on his contract in Naples.

More transfer news from Manchester City:

Manchester City 'have £62m Jose Gimenez bid rejected'
Atletico Madrid reject a £62m bid from Manchester City for South American defender Jose Gimenez, according to a report. Read more.

Lyon 'reject player-plus-cash bid for Houssem Aouar'
Lyon reportedly reject an offer of £31.2m plus a player from Arsenal for highly-regarded midfielder Houssem Aouar. Read more.

Leonardo confirms Paris Saint-Germain were interested in Lionel Messi
Paris Saint-Germain sporting director Leonardo confirms that the French champions "thought about" moving for Barcelona's Lionel Messi. Read more.

Leeds United closing in on £17.6m Josko Gvardiol signing?
Leeds United are reportedly closing in on the signing of Dinamo Zagreb defender Josko Gvardiol, who could cost in excess of £17m. Read more.