No financial details were given but Inter said under the agreement Chelsea would have the option to buy the 17-year-old for the next three years and the keeper would attend training sessions in London during the close season.
"This (deal) has saved us from bankruptcy and owing to it we'll soon be able to pay our players the salaries the club owes them since June," Inter director Branko Laljak told local newspaper Vecernji List.
Inter, who are joint 11th in the 16-team Croatian championship, confirmed on their website they had agreed the deal with Premier League Chelsea.
Last month the west London club were banned by soccer's world governing body FIFA from buying players until January 2011 after being found guilty of inducing a player to break his contract with another team.
Asked if the Delac deal was a way round the ban, Chelsea coach Carlo Ancelotti said: "No, absolutely not.
"He is a young goalkeeper and this is a solution for our future, not for the present. We put a lot of attention on young players in every part of the world and if it is possible to take them we want to do this.
"I think FIFA are happy (with the deal)," Ancelotti told reporters.
