During her trip to a cabinet meeting in the South, Ms Yingluck visited Nakhon Si Thammarat's Phra Mahathat Woramahawihan temple, for which the government plans to seek Unesco listing as a World Heritage site.
At the temple, Culture Minister Sukumol Khunploem told the prime minister that the Unesco World Heritage Centre in Paris will include the temple on its tentative list on Sept 19 next year.
Officials will carry out landscape decorations at the site and a working group will produce a complete report on the temple in Thai and English by December next year to back the World Heritage status request. Nakhon Si Thammarat authorities will also work out a master plan for the heritage bid.
As Ms Yingluck was heading to the temple, southern conservationists gathered on Ratchadamnoen Road in Muang district to protest against heavy industrial projects that they claim could have negative impacts on the environment and on local residents.
They obstructed traffic by lying on the road and holding posters, waiting for Ms Yingluck's delegation to pass in the same direction.
The demonstrators, led by conservationist Songwut Pattanakaeo of Tha Sala district, oppose a coal-fired power plant and petroleum and industrial port projects in the South and are calling on the government to protect the region and its seas, which are important for the country's food security. They pointed out that industrial projects in the South contradicted the United Nations' call for the international community to protect food sources in case of future crises.
The demonstrators ended their rally as Ms Yingluck's delegation left Muang district for Sichon district.