Thousands of people gathered on parliament grounds in Samoa this morning to celebrate 50 years since it declared independence from New Zealand.

The national holiday is marked with celebratory events every year but this year's anniversary was "momentous", the country's Head of State Tui Atua Tupua Tamasese Efi told the crowd.

It was a solemn affair, a time to remember, forgive and embrace the strong friendship between New Zealand and Samoa, he said.

Crowds of people of all ages listened intently to his words, and sang and marched after the formal speeches.

The sole survivor of the group that established the constitution calling for independence raised the nation's flag as the audience sang the national anthem.

A New Zealand contingent, including Governor General Sir Jerry Mateparae, MPs, many police of Samoan descent and the Navy Band, travelled to Samoa for the occasion.

Mateparae has spoken of how there have been "more ups than downs" over the last 50 years and how the relationship between the two nations continues to grow stronger.

The support New Zealand provided to Samoa in the wake of the 2009 tsunami, and that which Samoa gave to New Zealand after the 2011 Christchurch earthquake, only served to strengthen it even more, he said.

But the relationship has not always been positive and the pain which was caused by New Zealand's governance of Samoa still lingers, Tupua said.

Samoa became a German colony in 1899 but New Zealand took control during World War I and the islands became a mandated territory under the League of Nations.

After World War II Samoa was a United Nations trust territory administered by New Zealand until it gained independence - the first Pacific island to do so - in 1962.

On the 40th anniversary former New Zealand Prime Minister Helen Clark apologised to the people of Samoa.

She apologised for when the New Zealand government allowed a ship full of people with influenza to dock in the Samoan port in 1918, which contributed to the deaths of one in five Samoans, and for the shootings of non-violent protestors by New Zealand police in 1929.

"The redemptive power of her gesture and her words will live on in our hearts," Tupua told the crowd this morning.

"In all this remembrance we take note that this 50th year is a sacred year. The jubilee celebrates the power of remorse and forgiveness," he said.

"We believe in the redemptive power of forgiveness and remorse."

Talking to people in the crowd, they say they are thankful for the relationship between the two countries but are also pleased that their country is independent from New Zealand.

However, while Samoa is an independent nation, it is heavily reliant on aid and tourism, which took a hard hit after the tsunami but which is now flourishing once again.

The anniversary celebrations will continue for days to come. Thousands are expected at a UB40 concert and fireworks display tonight. Waka races will be held afterwards.

Earlier, the government announced it would release 35 prisoners from jail, saying they will be pardoned as part of the independence celebrations.

- © Fairfax NZ News