Washington, Oct 10 (IANS): Union workers at THE Volvo Group-owned Mack Trucks went on strike after a majority of the US company's union members in Pennsylvania, Maryland and Florida rejected a tentative agreement.

Covering 4,000 unionised workers, the tentative agreement differs based on location and job, reports Xinhua news agency.

For many Mack employees, it included about a 19 per cent wage increase, $3,500 ratification bonus and an increased 401(k) contribution.

It reduced the length of time to the top wage by one year to five years.

But the tentative agreement doesn't include reinstating pensions, a cost-of-living adjustment or a shorter workweek.

The United Auto Workers (UAW) representing Mack workers in the three .S states reached this tentative agreement with Mack Trucks on October 1.

In a letter to Volvo Trucks, the parent company of Mack Trucks, UAW President Shawn Fain said UAW members and workers across the country are seeking their fair share in wages and benefits.

"I'm inspired to see UAW members at Mack Trucks holding out for a better deal, and ready to stand up and walk off the job to win it," Fain was quoted by The Detroit News as saying in the letter.

"The members have the final say, and it's their solidarity and organisation that will win a fair contract at Mack."

In response, Mack Trucks President Stephen Roy said in a statement on Sunday night that the company is "surprised and disappointed" that the union chose to strike.

Mack is part of the only heavy truck manufacturing group that assembles all of its vehicles and engines for North America in the US, competing against trucks built in lower-cost countries, said the statement.

The company is committed to collective bargaining and is confident both sides will reach a deal that delivers competitive wages and benefits while safeguarding the company's future, it said.

Rejection of the tentative agreement may result from high expectations UAW has set in bargaining with the Big Three U. automakers, local media reported.

In its talks with the Big Three, the UAW has asked for a 36-per cent wage increase over four years.

Ford has offered 23 per cent so far, and the other two firms are at 20 per cent.

With Mack workers staging their strike on Monday, the total number of UAW members that are on strike now exceeds 30,000 across 22 states, the union said Monday.

Founded in 1900, Mack is one of North America's largest producers of heavy-duty trucks, and its trucks are sold and serviced in more than 45 countries.