"The matter is in the hands of our lawyers. That said I am mindful of the damage already being caused and we will think carefully as to how we pursue this."
The money is part of a £2m agreement signed last October and designed to provide an extra £1m per season for two years.
Stoke chairman Gunnar Gislason said: "We haven't considered the English directors not honouring the agreement. They are men of their word and have proven to be so."
He also denied that the Icelanders had breached the shareholders' agreement by their handling of Pulis's dismissal, adding: "The agreement is about informing them, asking their opinion and taking account of their views.
"I felt sometimes that the minority shareholders felt that the agreement gave them a right for a majority vote on any decision, but that isn't so.
"If our views are different then of course it is the responsibility of the majority shareholders to take the decision.
"I can understand they are disappointed and it will take a few days and weeks for them to get over that. But when the dust has settled, I think they will see things in a better perspective."