By Alastair Lawson
BBC correspondent in Dhaka
Hundreds of thousands of people across Bangladesh have taken part in celebrations to commemorate International Mother Language Day.
Bangladeshi lawyers praise the language martyrs
At a ceremony in the capital Dhaka both the prime minister and president paid homage to at least five language day martyrs who, 51 years ago, were shot by Pakistani security forces.
The protestors in 1952 were demanding that Bengali should have the same status as Urdu and be officially recognised as a national language.
The refusal of the Pakistani authorities to agree to their demand motivated many people to fight in the Bangladeshi struggle for independence, which culminated in Bangladesh's separation from Pakistan in 1971.
Today the Bengali language is a source of great pride and reverence for many Bangladeshis. It is a powerful unifying influence in a country where the two main political parties are bitterly divided.
In fact it is such a powerful and emotional issue that Bangladesh was instrumental in persuading the United Nations Educational Scientific and Cultural Organisation (Unesco) to designate 21 February as International Mother Language Day.
The commemoration had a festive atmosphere
During Friday's commemorations, many of the thousands of people who attended the ceremony at the Shaheed Minar (Martyrs Memorial) in Central Dhaka did so in bare feet. They were dressed in black to honour those who died.
"I am here because I want to pay tribute to our language day martyrs who played such a key role in helping Bangladeshi people to realise their dream of independence," said Mohammed Mofizuddin, one of those taking part.
Earlier in the day the prime minister and leading members of the cabinet and opposition laid wreaths at the Martyrs Memorial.
This year's ceremony was a mixture of the sombre and the joyful.
While some chose to walk silently or sing songs dating from the war of independence, there was on the sidelines a carnival atmosphere in which huge crowds watched pantomime and theatre performances near the Martyrs Memorial.
Those attending were watched by a strong security presence which included armed police.
That was in part because earlier police found and defused two small bombs at the Martyrs Memorial in the northern town of Rajshahi.