Dinamo Zagreb defender Filip Benkovic is reportedly set to undergo a medical at Leicester ahead of a move to the 2015/16 Premier League champions.
With the future of Harry Maguire still in doubt amid reported interest from Manchester United, the Foxes are looking to strengthen a backline that looked weak at certain points last season.
Croatia Under-21 international defender Benkovic, who has interested Chelsea and Borussia Dortmund in the past, is now likely to join Leicester after a fee of £13m was agreed with Zagreb, according to HITC.
Earlier on Tuesday, Sky Sports also claimed a 'broad agreement' had been reached and that Benkovic would fly to England to complete the deal.
Defensive reinforcements have been a priority for Leicester towards the end of the summer transfer window but they were recently knocked back in their pursuit of Brentford's Chris Mepham after being told it would take more than a £20m bid for the Bees to consider selling.
Leicester have recently lost Robert Huth, who left the club following the expiry of his contract, and Aleksandar Dragovic, who returned to Bayer Leverkusen after his loan spell.
The Foxes have signed Jonny Evans, James Maddison, Ricardo Pereira, Danny Ward and Rachid Ghezzal so far this summer but have also sold Riyad Mahrez to Manchester City, while they still could lose Maguire to United.
Puel has reiterated his desire to keep the England international, telling Sky Sports: "For me it's good for Leicester to keep a valuable player, and it's important to show good ambition for the next season.
"I can understand some speculation about our player because he has good attributes, but I am happy to keep him and hopefully start a great season.
"We lost Riyad Mahrez, who was a very good player for us. After Riyad it was important to keep our players and add some good players to strengthen the team."