BANGKOK:Thai street food sellers have earned the nickname "CIA" for the intelligence that helps them reach protests not only before police, but before many protesters too.

Selling everything from fishballs and fried chicken to dimsum and coconut ice cream their business is booming as tens of thousands of people take to the streets in protests against the government and the monarchy.

By the time most protesters show up, the first hawkers are there with mobile food carts.

"We have to follow the news very closely. We have formed a chat group after protesters gave us the nickname 'CIA'," said 29-year-old seller Petch. They named their mobile messaging group to share information "CIA Mobile Fishballs for Protests".

The sellers are ready to move in an instant and use their mobile phones to scrutinise announcements from protest groups, which announce protest sites at the last minute to confound police.

"They arrive even before us," commented 28-year-old protester Ploy at a protest by tens of thousands of people on Wednesday.

Protests, which started in July, grew even bigger last week after they were banned by Prayuth Chan-ocha, the former military ruler the protesters seek to oust. They also want to curb King Maha Vajiralongkorn's powers.

For some, the protest is not only a source of income.

"This cart doesn't sell to soldiers and police. Prayuth get out," says the sign on the cart of pop drink seller Komsan Moonsan, 44, whose wife and children also bring their carts to protests. Last Friday, he was hit by water cannon.

"I’m both here to sell and to support the protesters. I hate Prayuth very much," he said, complaining that under Prayuth's rule his income fell to 700 baht ($22) a day from 2,000 before. At protests, he reckons to make 1,000 baht a day.

Thailand's economy was the slowest growing in Southeast Asia after Prayuth first took power in a 2014 coup and it has taken a bigger hit than any in the region as the coronavirus stopped the vital flow of foreign tourists.

"I go to every protest," said 37-year-old Win, another fishball seller. "The stuff is sold out within only a couple of hours."