Shoprite are now using Mezeron as well as the Steam Packet for transporting freight.
Here isleofman.com publishes Unite's statement in full as well as a response from Mezeron and a statement from Shoprite which addresses the issues raised.
Steve Salter, from the Unite union, said: "Unite has just over 30 members working at the Steam Packet company and we are appalled that this government remains inactive over a situation that not only could put our members jobs at risk which is serious on its own but this could also affect staff working in tourism and other sectors of employment on the Island.
"The Steam Packet has served this Island for over 100 years now through good times and difficult times. It has its knockers but it has been a good servant to the Island's population on the whole.
"Our members within this company benefit from trade union recognition agreements and enjoy UK industry standard rates of remuneration for the work that they do.
"If this government does not act quickly over this matter not only will there be jobs lost but each and every person on this Island could end up losing out in some way or another.
"It is also worrying that two of the Island's biggest retailers have decided to move their freight to Mezeron.
"We are all in this together now and if we want to ensure that we have a reliable passenger service for the next 100 years we need to throw our weight behind the IoM Steam Packet Company which on the whole employs local employees who pay local taxes and who contribute to the Island's economy.
"The RMT, Nautilus and Unite will be informing the public through a leaflet distribution campaign over the next few weeks in various areas of the Island to highlight how precarious the situation is."
isleofman.com contacted Mezeron for its reaction to the statement. This is the reply in full.
"A number of false accusations have been made about our operations on the Island.
"This is extremely disappointing, given our long term commitment to Island, its residents and the Manx economy.
"To be clear:
"Mezeron is and always has been a Manx company, founded in Ramsey in 1983.
"We are a small freight operator with a big commitment to the Island, our head office is here, we employ local people who live and work here on the Isle of Man.
"We specialise in freight. Our service complements that of the Steam Packet, much as the easyJet air service complements the Steam Packet passenger service.
"For some businesses who want a roll On roll off service we cannot offer that and are not seeking to do so.
"That is for the Steam Packet. For others, our freight offering is more appropriate, including those seeking to leave from Liverpool.
"We are committed to seeing the Manx economy grow - it is in all our interests. We believe that this new service will help do just that.
"Mezeron is a Manx business bringing competition for the benefit of other businesses on the Island."
The response also featured the following information.
"Mezeron Limited is a financially sound company registered in the Isle of Man General Registry under the Number 23054 on the 30 Nov 1983.
"Mezeron Limited owns the vessel MV Silver River which is registered under the Isle of Man flag and employs Isle of Man seafarers.
"Mezeron Limited has grown under its managing partner Capt Norman Leece from employing about 20 staff to employing about 35 staff in 2010.
"All directors of the company are Manx residents for more than 10 years.
"Mezeron has two vessels on charter which are registered in an EU country, employ EU seafarers that pay tax and social contribution in the EU - Estonia - a member of the EU since 2004 with a population of about 1.4 mill."
A new statement regarding Shoprite's position is expected however this is an earlier statement which addresses some of the issues.
Shoprite chief executive Andrew Thomas said: "Isle of Man Steam Packet Company and Mezeron are contracted on Shoprite's behalf to transport goods from the UK to the Isle of Man.
"By using both sea carriers we are able to ensure that goods arrive on the Isle of Man, and are transported into our stores, in a timely and cost effective manner.
"Using more than one departure port from the UK also ensures that we are able to minimise the distance that our goods are transported to the departure port which represents a significant carbon saving and reduces the road miles that our goods travel.
"We are also able to reduce our costs by working with multiple carriers and Shoprite's customers will start to see the benefit of these savings as we are investing significant sums in ongoing re-development programmes in most of our stores.
"All three operations responsible for the transportation of Shoprite's freight on the newly announced route from Seaforth – Graylaw Manx, Mezeron Ltd and Mezeron's parent company Dohle (IOM) Ltd are registered in the Isle of Man, have traded here for 25, 27 and 21 years respectively and currently employ over 120 local people between them, all of which is important to Shoprite as the company actively supports businesses that are domiciled in the Isle of Man as this in turn benefits the local economy."
Also see: Steam Packet release new statement on freight situation