Kolkata, Dec 4 (IANS): West Bengal Chief Minister Mamata Banerjee Wednesday said the opposition's "discourteous" decision to boycott the platinum jubilee celebrations of the state assembly was tantamount to insult of the nation and the state.

"There may be arguments and disagreements, but we should not forget the courtesy expected from us. A party may come and go but democracy continues forever," said Banerjee during her address on day one of the three-day closing ceremony.

"I don't know why can't they (opposition) remember this, but I wish god forgives them for this," she added.

The Congress and the Left Front led by Communist Party of India-Marxist (CPI-M) decided to boycott the closing ceremony of the celebrations, accusing the ruling Trinamool Congress of "misbehaviour with opposition members inside the assembly as well its effort to destroy the democratic set-up in the state".

Banerjee said the CPI-M had earlier been "whimsical" too about attending the assembly.

"From 1972-1977 when Congress's Siddhartha Shankar Roy was the chief minister, the CPI-M boycotted (assembly) for five years. Why? Because the popular mandate did not go in their favour. Because they were not voted to power, they did not attend the assembly," the chief minister said.

"I will attend the assembly when it suits me and vilify it when it doesn't - this is not acceptable. When you vilify the assembly, you dishonour the country and the state," opined Mamata Banerjee.

Banerjee asserted that despite arguments and disagreements, the importance of the event demanded the participation of all parties.

"In parliament, there is the president, speaker, ruling party, opposition. There may be arguments and disagreements, but we always work together. Whenever there is an event like this, whether in parliament or assembly, it is not desirable that we are not part of it," she said.

"We cannot boycott, it's a protocol," Banerjee said.