This includes 16 billion baht from the government's flood prevention budget, which the NACN believes is in Hong Kong.
NACN secretary-general Mongkolkit Suksintharanon yesterday testified and submitted information about alleged corruption in four schemes to the Senate panel on corruption investigation and good governance.
The four schemes are the 120-billion-baht flood prevention project; the 5.3-billion-baht purchase of vocational education equipment; the 400-billion-baht rice-pledging scheme; and evasion of taxes on imported luxury cars, which the watchdog claims has caused about 60-80 billion baht in losses to the state.
Mr Mongkolkit said he had handed over evidence implicating three politicians and one senior civil servant in corruption in the purchase of educational equipment for vocational schools.
The politicians' names begin with the initials "N", "Ch", and "S" while the state official's name begins with the letter "S", the anti-graft activist said.
The Senate panel, chaired by Sumol Sutaviriyawat, also heard about the alleged siphoning of 16 billion baht from Thailand to Hong Kong.
Mr Mongkolkit claimed to have heard from Hong Kong authorities that they confiscated 16 billion baht, suspecting the money to be the proceeds of graft.
"Money illegally obtained from these schemes are transferred out of the country through tour operators and gold traders," Mr Mongkolkit said, without giving further details.
He called on Ms Sumol's panel to form an investigation team to look into the siphoning of money out of the country. The panel should also summon representatives from the tourism and gold businesses for questioning, he said.
When contacted, Hong Kong authorities denied any knowledge of the seizure of 16 billion baht, according to Justice Minister Pracha Promnok.
Mr Mongkolkit insisted that the NACN's information about the seizure of the 16 billion baht was solid.
The network obtained the information from the Hong Kong-based Independent Commission Against Corruption, which contacted the network through former National Anti-Corruption Commission secretary-general Apinan Issarangkura na Ayutthaya, he said.
"We do have in-depth information [about the money transfer], but we can't make it public because it is highly-confidential," Mr Mongkolkit said.
He also confirmed that deputy permanent secretary for Justice Dusadee Arayawuthi had some information about the 16-billion-baht money transfer.
Pol Col Dusadee is a former Public Sector Anti-Corruption Commission secretary-general, and once led an investigation into suspected graft in the Pheu Thai government's flood prevention and rehabilitation projects.
Pol Col Dusadee, however, said yesterday that he knew nothing about the siphoned money, but said he was ready to talk to the Department of Special Investigation (DSI) if the agency launches an investigation into the matter.
DSI director-general Tarit Pengdith yesterday said he would summon Pol Col Dusadee and Mr Mongkolkit for questioning after the Pheu Thai Party asked the DSI to investigate whether money siphoning had taken place.
Pheu Thai believes the NACN fabricated the story to attack the government. The ruling party yesterday submitted a letter to the House anti-corruption committee asking for an inquiry into the Hong Kong allegations.
The letter was submitted by Pheu Thai spokesman Prompong Nopparit to Pol Lt-Gen Viroj Pao-in, chairman of the House anti-corruption panel.
Pol Lt Gen Viroj is a Pheu Thai Party list-MP and acting leader of the party.
Mr Prompong said both Pol Gen Pracha and the Anti-Money Laundering Office had dismissed the allegations as groundless, as have Hong Kong authorities.
The Pheu Thai spokesman said that as a result the party wanted the House anti-corruption committee to investigate the motives behind the accusations.