Thailand will lift a ban this week on overseas travel by some politicians, the defense minister said on Monday, more than two years after the measure was imposed.

Over the last few months, Thailand's military government, which took power in a May 2014 coup, has begun easing some of its strict restrictions on political activity, in the run-up to an August referendum on a draft constitution.

The lifting of the ban showed the junta's trust in politicians, Deputy Prime Minister and Defense Minister Prawit Wongsuwan said.

"Politicians who have no legal cases are able to travel," Prawit told reporters. "Whether they go abroad and then take part in political activities is up to them."

The lifting takes effect on Wednesday, the junta has said.

But it excludes politicians such as former Prime Minister Yingluck Shinawatra who faces criminal charges over alleged corruption in her government's rice subsidy program.

After the army took power in a move it called necessary to restore order, the junta banned political activity and ramped up prosecutions under tough sedition and royal defamation laws.

The junta summoned hundreds of politicians, activists and journalists for so-called attitude adjustment sessions, often at military bases.