"A section of the former royal family had tried to merge Tripura with the then East Pakistan. Efforts were also made to merge the state with Assam or West Bengal," Sarkar said at a function here.
He said former Tripura chief minister and tribal leader, Dasaratha Deb, led a struggle against the move to merge Tripura with then East Pakistan or Assam or West Bengal.
The function was organised by the tribal welfare department to unveil a bust of Dasaratha Deb.
According to historians, a section of the erstwhile Tripura royal family had tried to merge the state with then East Pakistan. But the last king of Tripura, Bir Bikram Kishore Manikya (1923-1947), before his death had expressed his desire to keep Tripura with the Indian union.
Sarkar, who has been ruling the state since 1998, said: "Tripura's Left Front government would not allow any attempt to divide the state. A move was on to create a separate state out of Tripura."
He said a small political party has now started demanding a split in Tripura and it recently organised an unruly rally in Agartala in support of the demand.
The Indigenous People's Front of Tripura (IPFT), a tribal political party, has been demanding a separate state to be carved out of Tripura by upgrading the Tripura Tribal Areas Autonomous District Council (TTAADC).
The TTAADC was formed by amending the Indian constitution in 1985 to improve the socio-economic condition of the tribals, who constitute one third of Tripura's 3.7 million population.
The chief minister also said the four-and-a-half decades old terrorism in Tripura has largely been tamed, but some people and political parties are trying to revive it.
"Based in Bangladesh and Myanmar and supported by ULFA (United Liberation Front of Asom) and NSCN (IM) National Socialist Council of Nagaland (Isak-Muivah), the Tripura militants are trying to create trouble in the state," said Sarkar, who also holds the home portfolio.