Three Buddhist monks have been arrested in Burma after authorities found more than 4million methamphetamine pills in one of their cars and in their monastery, police said on Tuesday.

One of the monks, named Arsara, was stopped on Sunday as he drove in northern Rakhine state, which borders Bangladesh, Officer Maung Maung Yin said. Authorities had been tipped off that the monk was carrying an illegal haul.

Maung Maung Yin said an anti-drug task force found 400,000 pills in the monk's Toyota Kluger.

A subsequent search of his monastery turned up 4.2 million pills along with a grenade and ammunition.

Buddhist monks Khone Na La also known as Thein Shwe (left), Pyin Nyar Nanda also known as Aye Lwin (center), and Arsara also known as Min Naing (right) were arrested in Burma after an anti-drug task force found 400,000 pills in Arsara's car

In total, three Buddhist monks were arrested: Arsara also known as Min Naing, Pyin Nyar Nanda also known as Aye Lwin, and Khone Na La also known as Thein Shwe.

Arsara was part of the Shwe Baho monastery, according to Irrawaddy.com.

A statement from the office of Burma's leader, State Counsellor Aung San Suu Kyi, said that one million kyats ($769) in cash was also found in the vehicle.

Burma is a major producer of methamphetamine, usually smuggled from the northeast to neighboring countries. It is also the world's second biggest producer of opium, from which heroin is derived.

In 2015, drug prosecutions in Burma have jumped about 50 per cent from the year before to 13,500, which police say reflects the growing drug trade.

Last year, a record 98million stimulant tablets were confiscated by police across Asia.

A subsequent search of his monastery turned up 4.2 million pills along with a grenade and ammunition

'This is not a normal case, and when we were informed that the monk was arrested, we were all shocked,' said Kyaw Mya Win, a township police officer.

Asked about the case, the director general of the Religious Affairs Ministry, Soe Min Tun, acknowledged some surprise.

'It is not a very common case, but not impossible to happen. What will happen to the monk is that he will have to give up his monkhood right away and face trial as an ordinary person,' he said.

Police said they were still questioning the monk Tuesday.