At least 28 people were injured in explosions near Bangkok's Victory Monument on Sunday. The city's Erawan Emergency Center reported that several hospitals across the city were treating blast victims. It was not immediately clear how serious their injuries were.

"Among these, seven people were seriously injured," director general Suphan Srithamma said.

As has been the case in previous attacks this week - including a grenade attack on Friday that killed one person and left nearly 40 injured - authorities could not confirm who was behind the violence.

Sunday's attack came less than a day after an unidentified gunman wounded a 54-year-old man at a protest site in Bangkok. The man was reportedly in stable condition at a local hospital.

Thailand's supreme armed forces commander commented on the rise in violence as protesters continued their "shutdown" protests this week.

"Now all of us need to help each other in taking care of our own nation," supreme armed forces commander Thanasak Patimapakorn said on Saturday.

"The relationship between the government and the army is normal…We need to respect law and order," he said, adding that "all sides should come together and talk to find a solution."

Obstinate protests

Demonstrators have been demanding the resignation of Prime Minister Yingluck Shinawatra, whom they have accused of operating as a political proxy for her brother, former Prime Minister Thaksin Shinawatra.

Two months ago, Yingluck's government attempted to pass an amnesty bill which would have cleared the way for her brother to return to power. The move prompted a political crisis. In a bid to end the standoff, Yingluck called for snap elections for February. However, protesters rejected the proposal and are demanding an unelected "people's council" be appointed to reform the political system.

This week's "shutdown" protests have been aimed at causing major disruptions to the government and businesses in the capital city by occupying its main roads across seven protest sites.

kms/tj (AP, AFP, Reuters, dpa)