Agartala, Oct 14 (IANS): The outlawed National Liberation Front of Tripura (NLFT) terrorist outfit has called upon tribals to observe a "Black Day" on Sunday to protest Tripura's merger with the Indian Union and for restoration of the "historical rights" of tribals.

In a statement to media houses, the NLFT called on tribals to observe October 15 "as a mark of protest, solidarity, and black day against the colonial rule. We appeal to the younger generations, who are future of the society, to come forward in this regard."

It said: "On October 15, 1949, India took control over the royal administration, disbanded the royal army and put martial law in place till 1952 to suppress any resistance.

"At the end of 517-year rule (1432-1949) by 184 kings, on October 15, 1949, the erstwhile princely state came under the control of India according to a merger agreement signed between Kanchan Prabha Devi, then regent maharani, and the Governor General of India.

"The NLFT for the past 28 years has been spearheading the struggle for the restoration of the historical rights of the tribals of Tripura and to protest against the settlement of the illegal immigrants from Bangladesh."

The NLFT strongly criticised the former Left and Congress leaders for facilitating Tripura's merger with the Indian Union.

A senior police official said that the NLFT is planning to indulge in violence before and during the next Assembly elections due in February next year.

"Four NLFT guerrillas who fled from their Bangladeshi hideout and surrendered to the Border Security Force (BSF) recently, told this to the police interrogators," the official said.

NLFT cadres undergo arms training in several hideouts in Bangladesh, which shares a 1,880-km border with India.

Banned in 1997, the outlawed outfit had sought Tripura's secession from India.