Coutinho moved to Liverpool in an £8.5m deal from Serie A champions Inter Milan in the 2013 January transfer window under Klopp's predecessor Brendan Rodgers.
Liverpool have repeatedly stated Coutinho will not be sold and their position is strengthened by the five-year contract he signed only last season. The Sun says that Liverpool are "adamant" Coutinho is going nowhere but there is growing speculation that if Barcelona up their offer to £120m then the Reds will find it hard to resist.
"Looking at the financial aspects, there is no pain barrier so that we'd give in when a certain fee has been reached", Klopp said.
Steven Gerrard has commented on the Philippe Coutinho transfer saga and said that the player must decide whether he wants to try and "create a war" by forcing a move away from Liverpool.
The danger for Liverpool's owners is balancing whether they can allow this deal to go through against keeping a player who wants to leave.More news: Please don't put your feet up on the dashboard
His compatriot's move to Paris Saint-Germain has prompted the interest from Barca and they have already had one bid of £72m turned down by the Merseyside outfit.
Supporters will hope that Liverpool continue to maintain their firm stance on the matter and manage to hold onto their star attraction for the new season.
However, their latest proposal of €85 million plus €15 million in add-ons has not tempted Liverpool to allow the transfer of Coutinho to go through.
The Liverpool manager added: "Today, no player on the planet is untouchable".
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"We are not a selling club so they will do everything in their powers for him to stay".