The United Auto Workers' negotiations with General Motors hit a bump on Sunday after the former rejected the latter's latest offer.

The parties have been in talks over a new four-year labor contract between GM and the company's striking workers. But the newest proposal from the US automakers, the largest in the country, has only mirrored the one previously rejected by the UAW.

That is according to UAW vice president Terry Dittes, who penned a letter to members informing them of the newest developments. Said letter was obtained by Reuters and bears notes of disappointment, with GM being accused of being unwilling to provide satisfactory compensation.

"These negotiations have taken a turn for the worse," Dittes said (h/t Autoblog).

PREVIOUSLY: With Both Sides Digging In For The Long Haul, GM Autoworkers Strike Sees No Sign Of Ending

via freep.com

"We, in this union, could not be more disappointed with General Motors. The company has shown an unwillingness to fairly compensate ... the UAW."

Dittes said the UAW made an offer covering wages, signing bonuses, job security, profit sharing and various other issues to GM this past Saturday. The manufacturers are said to have returned with a counteroffer the following day which "did nothing to advance a whole host of issues."

GM's 48,000 UAW members went on strike on September 16 over their discontent with the conditions at plants. Workers are understood to be disgruntled about pay and job security, they're also very dissatisfied with the current state of affairs as it relates to the sharing of company profits, while healthcare benefits are of major concern as well.

The company has been meeting with the UAW on a daily basis since then but the parties have not been able to find common ground and appeared to have hit an impasse on Sunday.

The latter body also wants GM to give certain assurances regarding future products from various plants and they're urging the company to pull assembly work back from the likes of Mexico and China.

On the GM side, the automakers insist that their labor rates are the highest in the industry, stating that they need to retain the ability to build vehicles in other markets to keep costs down.

According to analysts, the strike has already cost GM over $1 billion. LMC Automotive also reports that the manufacturers had lost production of 118,000 as of October 2.