BANGKOK May 19 (Reuters) - Labour unions representing workers in Thai state firms have called for a strike this week to force the government out, siding with street protesters who have been trying for six months to get a new prime minister appointed.
The State Enterprises Workers' Relations Confederation, whose members come from around 20 state firms, said its members would strike from Thursday in sympathy with the protesters, who say they are making one last push to oust the government.
"The ministers who remain refuse to resign, so we ask that state labour unions go on strike as of Thursday. Many are still discussing whether they will strike. But, big state organisations, including utilities and transport companies, have often sided with us," said Komsan Thongsiri, secretary-general of the confederation.
"We won't cut electricity or water, but if these remaining ministers don't step down, we might see something that we have never seen," he added, without elaborating.
The unions would join anti-government protesters from the People's Democratic Reform Committee (PDRC) to try to remove acting Prime Minister Niwatthamrong Boonsongphaisan and would take part in street rallies .
Sirichai Mai-ngam, president of the union at the Electricity Generating Authority of Thailand (EGAT), said his union would not be striking but would join the protests this week.
"We will definitely join the PDRC, but it will not involve any stoppage. This will not affect any operations of EGAT and we will not shut down," he said.
Unionisation in Thailand is low and mostly limited to the public sector.
Transport Minister Chadchart Sittipunt asked state employees on Monday not to take part in the strike.
The protests are the latest development in a decade-old conflict between Bangkok's middle class, powerful business families and the royalist establishment on the one side, and on the other side the mostly rural poor supporters of ousted former premier Thaksin Shinawatra, who now lives in self-exile.
The protesters, led by former opposition lawmaker Suthep Thaugsuban, took to streets of Bangkok in November demanding the removal of then premier Yingluck Shinawatra, Thaksin's sister.
She and nine other ministers were found guilty of abuse of power on May 7 and ordered to step down, and the protesters are now questioning the legitimacy of acting Prime Minister Niwatthamrong Boonsongphaisan, a member of her cabinet who replaced her.
They want remaining cabinet members removed to make way for an unelected prime minister to push through electoral changes to reduce the chances of Thaksin's allies winning power again.
Throughout the demonstrations, salaried employees from state enterprises have backed the anti-government campaign, alongside supporters from Bangkok's middle class.
Staff from national flag carrier Thai Airways Pcl gathered in their hundreds to receive protest leader Suthep when he dropped by its Bangkok headquarters last month.
The airline denied in January that flight delays were the result of action by staff in support of the protests. (Additional reporting by Khettiya Jittapong and Manunphattr Dhanananphorn; Editing by Alan Raybould and Simon Cameron-Moore)