The life-size dummy, dressed in a blue shirt and grey trousers and wearing a rubber mask of the Prime Minister, was hung from Winter's Gibbet near Elsdon.
The effigy, accompanied by the slogan 'Fight prejudice, fight the ban', was placed there just days after MPs forced through a ban on hunting with hounds using the Parliament Act after the House of Lords rejected a compromise by a majority of 39.
The Hunting Act is set to come into force as early as February 2005.
Michael Hedley, of the Border Hunt, has not seen the effigy but feels it is representative of the general attitude towards Mr Blair over the issue.
He said: "Everyone feels bitter and badly let down. We've been lied to all of the time. The Prime Minister is not being strong enough to stand up to the backbenchers. He's spineless."
Richard Dodd, North East director of the Countryside Alliance, said:"It was always felt there was anger in the countryside. When they pass the law it is going to have a major impact financially. There are a lot of people who are going to lose their jobs or livelihood.
"I think they're being kind hanging him by his neck."
Ian McKie, master of College Valley and North Northumberland Hunt, also knew nothing about the effigy, but said: "I think it just re-enforces the strong views of everybody involved in hunting. The opinion they have on what this Government has done to a way of life that effects a lot of people."
The ban brings with it more than 200 job losses across Northumberland and would have a major impact on rural communities, but Mr McKie said the fight 'has only just begun'.
Mr Dodd said Countryside Alliance will challenge any written laws until February 18 to ensure they are correct.
Mr McKie said after February he will continue to employ staff and look after the hounds.
He said: "It remains the resolve of everybody involved to try and reverse this ridiculous ban. We are committed to fighting it however long it takes. As a result we need to keep an infrastructure together.
"We will have to make cuts but we will look to the options we have and how to continue hunting peacefully within the law."
Mr Hedley said: "We've got land in Scotland so we will continue doing it there, but it's too early for any of us to know what the options are going to be. It's too drastic a move to say we're just going to shut up shop."