Thai Prime Minister Yingluck Shinawatra visits neighboring Cambodia Thursday in hopes of normalizing relations after a series of deadly border clashes.

Ms. Yingluck, who took office last month, is to hold talks with Prime Minister Hun Sen after a welcoming ceremony in Phnom Penh, and then proceed to Khemarin Palace to meet King Norodom Sihamoni.

Both governments say they are interested in restoring peace after border clashes this year killed 28 people and displaced thousands of villagers. Relations have improved dramatically since Ms. Yingluck came to office replacing the former government of Prime Minister Abhisit Vejjajiva.

The Bangkok Post newspaper Thursday quoted Ms. Yingluck saying economic issues could be discussed if the atmosphere is positive. Cambodia has proposed the joint development of oil and natural gas reserves in disputed waters in the Gulf of Thailand.

Thai officials also said Ms. Yingluck would press for the release of Thai nationalist Veera Somkwamkid and his secretary, who were convicted on espionage charges after crossing illegally into Cambodia earlier this year. Veera was a legislator with Mr. Abhisit's party at the time of his arrest.

Ms. Yingluck's elder brother, Thaksin Shinawatra, is also expected to seek their release when he visits Phnom Penh on Friday to deliver a lecture. Mr. Thaksin, who was ousted as prime minister of Thailand in a 2006 coup, served as an economic adviser to Mr. Hun Sen and enjoys a warm relationship with him.

Ms. Yingluck said she will not see or speak to her brother, who was convicted on corruption charges in Thailand while his political opponents were in office. Oppositions politicians say the government is obliged to try to bring him to justice.