"A total of seven persons have so far died in the landmine blast incident," DIG south-western range, S Syani, said.
The police had recovered four bodies from the site of blast and three others died in the hospital later.
Chief Minister Naveen Patnaik has termed the incident a "cowardly act".
The explosion took place near Mungarbhumi on Sunki ghat, barely one km from Andhra Pradesh border, in the Maoist- affected Koraput district, the officer said.
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The seriously injured personnel were taken to hospitals in Koraput in Odisha and Visakhapatanam in Andhra Pradesh.
The blast was suspected to have been triggered by the red rebels operating in Andhra-Odisha border areas, police said.
"Our men are facing problem in the rescue operation due to darkness," ASP (Koraput) V R Rao said.