Amicus has signed agreements with three international unions in a move to create a global trade union.
Derek Simpson wants to create a global body in a decade
It says it hopes it could help to stop multinationals from playing global employees off against each other.
With the Transport and General Workers Union, it will ballot their nearly two million UK members in February on a merger to take place in May.
Amicus has signed with IG Metall in Germany and the Machinists and the United Steel Workers in the US.
'Powerful single union'
It hopes there will be a global union in the next 10 years.
Amicus general secretary Derek Simpson said: "The world is changing and the new global realities involve transnational companies being able to trade off countries and workforces against each other.
"By establishing more positive links and working arrangements with trade unions abroad we can work together to prevent labour standards being eroded by ruthless global companies who show a ruthless disregard for their workers in the pursuit of even greater profits.
"Our aim is to create a powerful single union that can transcend borders to challenge the global forces of capital and I envisage a functioning, if loosely federal, multinational trade union organisation within the next decade.
"As a single union we will be able to focus on delivering better pay and conditions for our members and have the organising strength to reach out to new trade union members in our existing work places, as well as in new industries."