A statement issued by the President's Office on Monday night said those benched include Kagera Regional Police Commander (RPC) Augustine Ollomi and the Kyerwa Officer Commanding District (OCD), Justine Joseph.
The Officer Commanding Criminal Investigation Department (OC-CID) for Kyerwa District EveristKivuyo and the Kyerwa Officer Commanding Station (OCS) Robert Marwa have also been suspended.
The move comes following allegations that senior police officers in Kagera Region are involved in a criminal cross-border smuggling cartel by providing police escorts to smugglers of coffee beans and other items. Kagera is among the biggest coffee-growing regions in Tanzania.
"The police officers are being suspended to allow an investigation into their alleged involvement in coffee smuggling activity in Kyerwa District along with other allegations," the presidency said in the statement.
"President Magufuli has also instructed the Permanent Secretary in the Ministry of Home Affairs, Maj.Gen. Jacob Kingu, and Inspector General of Police (IGP) Simon Sirro to ensure that a thorough investigation is carried out and all relevant legal actions are taken if the allegations are proved."
The allegations against the senior police officers surfaced on Sunday during Prime Minister KassimMajaliwa's visit to Kyerwa District in Kagera Region.
Majaliwa said he had received reports that the Kyerwa OCD was being accused by fellow police officers of personally escorting coffee smugglers to cross the border to neighbouring countries. The OCD was not immediately available to respond to the allegations.
"It's very dangerous when the police force itself is involved in escorting coffee smugglers instead of stopping them," the PM said during his visit of Kyerwa District.
Majaliwa claimed he had also received reports that some dishonest police officers in Kagera Region were colluding with businessmen from a neighbouring country to facilitate the smuggling of coffee beans from Tanzania.
Why coffee matters
The Tanzania Police Force headquarters announced earlier on Monday that the Kyerwa OCD would be transferred to another station to pave way for an investigation into the allegations against him. But President Magufuli later decided to suspend all the four senior police officers, including the Kagera RPC.
Coffee smuggling from Tanzania to neighbouring Uganda has been rampant for many years, with criminal networks potentially raking in billions of shillings each year.
The illegal coffee export rings have been denying the government substantial revenue collections, with farmers lured by better prices for their produce across the border.
Tanzania, which produces mainly arabica and a bit of robusta coffee, is Africa's fourth-biggest coffee producer after Ethiopia, Uganda and Ivory Coast.
Tanzania fetched $154.2 million (over 350 billion/-) in 2016 from coffee exports, down from $162.2 million in 2015, according to Bank of Tanzania (BoT) data.
In terms of cash crops, coffee is the third-biggest foreign exchange earner in the country after tobacco and cashew nuts.
Kagera Region produces over 12,000 tonnes of coffee each year, with a significant amount of the crop reportedly illegally exported to Uganda due to better prices offered in the neighbouring country.
The government announced in July that all the coffee in the country would strictly be sold at coffee auctions in Kilimanjaro Region organised by the Tanzania Coffee Board (TCB) to curb illegal exports of the crop.
According to the Minister for Agriculture, Dr Charles Tizeba, the government was determined to smash the cross-border smuggling of coffee.