Two men died and three were injured by an explosion on the outskirts of Theni village in Butheedaung township on Thursday, said a statement from the office of State Counsellor Aung San Suu Kyi.
Security forces launched the operations after the incident and on Sunday discovered supplies of gunpowder and charcoal which they believed were being used to make landmines.
They "are still investigating the deaths, injuries and those involved in making homemade mines", the statement said.
Muslim nations to heap pressure on Myanmar over Rohingya
Northern parts of the western state have been gripped by violence since October, when a militant group claiming to represent the country's Rohingya Muslim minority launched deadly attacks on police border posts.
In the following months hundreds of Rohingya, most of whom live in Rakhine, are thought to have been killed in an army campaign to root out suspected insurgents. UN investigators said the campaign was so brutal it could amount to ethnic cleansing.
Tens of thousands have fled to Bangladesh, the latest chapter in years of persecution. The UN's refugee agency last week said almost 170,000 Rohingya had left the country since 2012.
Myanmar's government led by Nobel laureate Suu Kyi has dismissed the claims and said the probe would only "inflame" the conflict.
On Monday she was greeted by protests as she went to receive the Freedom of the City of London award, during a visit to Britain. She is also visiting other European countries.
The Rohingya Muslim minority are rejected by many members of the Buddhist majority as interlopers from Bangladesh and are denied citizenship.
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