Superintendent of the correctional home D Bhutia said, "seven of the 20 Kamtapuri activists, who had started fasting on May 27, were admitted to Malda Medical College and Hospital as their condition deteriorated."
Eight more such activists also joined the hunger strike demanding immediate release, he added.
Of the total 729 inmates, 55 are undertrial Kamtapuri activists who were arrested for their alleged links with the banned Kamtapur Liberation Organisation (KLO) and the Kamtapur Peoples Party (KPP) and lodged in the correctional home for nearly an year.
KPP Central Committee vice-president Subhas Burman said all the 55 people were innocent and demanded their unconditional release.
The objective of the KLO is to carve out a separate Kamtapur state comprising six districts north Bengal and four contiguous districts of Assam.