Led by Vichoksak Ronarongpairee, the group asked the governor to pass on the petition to Prime Minister Yingluck Shinawatra.
"The sum is huge and the government must thoroughly review this, or this could boost public debt and all Thais would have to shoulder responsibility in the long term," the leader said.
Of total sum, about Bt50 billion is allocated for the Land Bridge project to link Songkhla and Satun. Under the project, Pak Bara Port will be constructed in Satun, which will be linked with ports in Songkhla with a double-track rail.