Thai police have arrested a Buddhist monk on suspicion of embezzling 100 million baht ($3m; £2.2m) from his monastery, along with a suspected female accomplice he was filmed having sex with.

Phra Wachirayan Wi, a former abbot at the prominent 14th-Century Wat Phutthaisawan in the ancient capital of Ayutthaya, allegedly pocketed donations meant for the temple on more than 20 occasions over two years.

In Thailand, Buddhist monks take a vow of celibacy and also renounce material possessions. He was defrocked after his arrest. He has yet to comment publicly.

The latest arrests come just over a year after another sex-and-blackmail case involving senior monks rocked Thailand’s monastic community.

The 66-year-old was known for creating a highly-coveted coin amulet. Thai Prime Minister Anutin Charnvirakul reportedly owns some of his creations.

Thailand’s Buddhist institution has long been plagued with reports of monks breaking their vow of celibacy, trafficking drugs and committing financial crimes.

In July last year, police opened a hotline for people to report “misbehaving monks” after at least nine monks were found to have had sex with a woman. She then blackmailed them with photos and videos of the acts for nearly $12 million.

Police on Friday said they identified two streams of money linked to donation receipts Phra Wachirayan had issued in the temple’s name – one was meant for temple renovations, while the other was payment for amulets and other sacred objects.

“But the money from both streams did not enter the temple’s account. Not a single baht,” lead police investigator Pattanasak Bupphasuwan told a news conference, according to reports.

Police found cash and gold bars worth more than 100 million baht while raiding Phra Wachirayan’s residence on Thursday, with counting going on until late into the night, Thai news outlet The Nation reported.

While examining CCTV footage in the residence, police found a clip of him having sex with a woman on his dining table.

Authorities identified her as 47-year-old Punyavee Rungrueang, who has been arrested on charges of abetting a state official in illegal activities. She has yet to comment publicly.

Many monks in Thailand receive stipends from the government and are therefore considered state officials.

Police seized 35 gold amulets, along with about 1.5kg of gold bars and jewellery, worth an estimated 6.04 million baht, from Punyavee’s home.

Police believe Punyavee helped Phra Wachirayan manage his embezzled proceeds, noting that tens of millions of baht circulated through her bank accounts each year, The Bangkok Post reported.

Investigators say they started looking into the case in mid July, after receiving an anonymous tip alleging Phra Wachirayan of misconduct and misuse of temple funds.

Two or three other people could be involved in the case, they say.