Governor C.V. Ananda Bose observed the "West Bengal Foundation Day" on Tuesday ignoring vehement opposition from the chief minister who had told him in a letter on Monday that the state hadn't been formed on any particular date.

But Bose said he had celebrated the day based on an advisory from the Union government on May 11.

Mamata Banerjee said the chair of the governor must not be used to "play politics".

"Spent my entire life in Bengal, but never heard about any ‘State Foundation Day’," Mamata said while leaving the state secretariat on Tuesday. "This 'celebration' is being done with the sole purpose of defaming Bengal. It is being carried out with the purpose of insulting the soil of Bengal and the people of our land," she added.

Sources in the Trinamul Congress said that Mamata had called up Bose on Tuesday afternoon and grudgingly expressed her disappointment over his decision to go ahead with the event even after her strong disapproval.

"If BJP believes whatever they decide to celebrate, others have to agree to it, they are mistaken," the Trinamul chairperson said, hinting that the event planned by the Raj Bhavan was intended at expanding the saffron propaganda to observe June 20 as the foundation day of West Bengal.

On Monday, in a letter to Bose, Mamata had expressed her "shock" at the "unilateral" decision taken by the Raj Bhawan to commemorate the day. She had claimed in the letter that during her conversation with the governor on the phone the latter had admitted that not keeping the state in the loop about the decision was unwarranted.

The letter said "the state was not founded on any particular day, least of all on any 20th of June. Contrarily, the State was formed through the infamous Radcliffe Award".

However, the Raj Bhavan went ahead with its plans anyway. At the programme, Bose spoke on "zero tolerance" for violence and emphasised the right of the common people to vote freely.

But later in the day, it released a press note on "the factual position about the commemoration of Foundation Day of West Bengal" in view of "some apparent disinformation doing the rounds".

The release speaks of the May 11 advisory from the Union government that proposed that various states and union territories should observe their foundation days. "Till now, as per the Government of India advisory, Raj Bhavan has already observed five State Foundation Days, and celebration of West Bengal’s Foundation Day was in the sequence suggested in the Advisory," the release said.

It acknowledged that a letter was received from the state government on the late evening of June 19, which requested that the function is not held. However, on the same day, President Droupadi Murmu sent her greetings to the people of Bengal on the occasion of its foundation day.

"The contents of the letter received from the State Government will be treated with all seriousness and will receive priority attention and taken up with competent authorities for appropriate action," the press release read. No representative of the government was present at the Raj Bhawan during the event.

BJP sources said with the governor organising a grand event to commemorate June 20, the party's long-standing demand of declaring this day as the foundation day of the state has found some acknowledgment.

Suvendu Adhikari, the leader of the Opposition, led a march of lawmakers from the Assembly to the statute of Shyamaprasad Mukherjee at Red Road as a part of the party's day-long programmes to celebrate this day.

"We are happy (that the governor organised the event). This is surely a good thing and we thank him," Adhikari said about the event at Raj Bhawan. Taking a dig at the state government, Adhikari said that the finance department might not clear the expenses incurred by the Raj Bhawan for this event.

However, according to Mamata, both the Left parties and the Congress were also unaware of "this so-called 'Foundation Day". She reminded the Union government of the petition to rename West Bengal that has been pending with them for six years.

"We want the name changed because our officers have to wait for a long time during transfers, as alphabetically, ‘W’ of West Bengal comes way down the list. The central government has objection in changing Bengal’s name, but is planning to celebrate our ‘Foundation Day’. What can be more ironic than this?" she asked.