"I had no idea what happened then. It's startling," said a control officer, who anticipated the soldiers could have blocked satellite transmissions.

Hours later, UBC signals broadcast via Thaicom were shut down.

At first, there were negotiations to block only news channels - particularly CNN and BBC - but later all channels, including entertainment, were off air. The shut down was still in force at press time.

Thaicom III building on Phaholyothin Road also houses control facilities for Advanced Info Service, which operates a GSM mobile phone network. It was seized at about 8pm.

"No soldier went inside the building but we're terrified, seeing soldiers surrounding the building like that," said an AIS employee.  "Still, we waited until 11pm, after learning about the coup and seeing no violence. Then, we headed home."

However, AIS services are operating as usual.

There were also reports the Administrative Reform Council (ARC) sought to cut off all mobile phone networks, but operators talked them out of it because of emergency health situations.

Besides former Shin Corp media outlets, now owned by Temasek Holdings of  Singapore, the offices of other mass media including Nation Multimedia Group (NMG) have been encircled by troops.

At the office of NMG on BangnaTrad Road, 40 soldiers are stationed around the building. They claim to be here to "protect and provide security".

Those wanting to enter or leave the property were required to present identification.

Meanwhile all six freetoair television channels have suspended their normal programmes and are broadcasting songs praising His Majesty the King. There is an occasional broadcast for the ARC.

Channel 11, operated by the Public Relations Department, and iTV returned to normal broadcasts at 8.30am today.