Nepal on Sunday formally adopted a much anticipated and long-delayed constitution that took more than seven years to complete following a decade of political infighting.

Security was stepped up across the nation, with smaller political parties and ethnic groups opposed to the new charter issuing fresh threats of violence.

President Ram Baran Yadav signed the constitution and made the proclamation announcement, setting off a roar of applause from members of the Constituent Assembly in Kathmandu.

"We believe that the adoption of the new constitution has now opened the path for development of the country," Yadav told the assembly.

The new constitution replaces an interim one that was supposed to be in effect for only a couple of years but has governed the nation since 2007.

Thousands of people who gathered outside the assembly hall cheered after the announcement was made, waving the national flag as fireworks went off.

In the streets of Kathmandu, the capital, people lit oil lamps and candles and buildings were decorated with colored lights.

"Congratulations to all Nepalese" read a white and red banner strung across a street.

"This really long chapter is now finally closed," said Shyam Sharma, a student who watched the president's motorcade drive toward the assembly. "Now the country can focus on other important issues like developing the country, improving the economy. If these politicians had agreed a few years back, we would not have wasted so much time, energy and money."

The key part of the constitution, passed on Wednesday after a decade of bickering and violent protests, sets the country up as a secular federation of seven states, each with a legislature and chief minister.

However, some ethnic and religious groups say lawmakers ignored their concerns over how state borders should be defined. They want more states, including ethnically based ones, bigger territory for larger groups and more seats for ethnic minorities in parliament and government.

Laxman Lal Karna, a senior leader of the Madhesi ethnic group in southern Nepal, said the new constitution failed to address many of the issues and that protests would continue.

The violence over the past several weeks has left at least 45 people dead. Police said clashes between officers and protesters on Sunday left one demonstrator dead near Birgunj town in southern Nepal.

The three main political parties backing the constitution have made a fresh appeal for Madhesi to join talks.

"They may disagree with the size and makeup of these states, but that is not a really big issue," Prime Minister Sushil Koirala said Saturday.

There are more than 100 ethnic groups in Nepal, and some say the new constitution still limits their representation. Though members of parliament are to be chosen through a proportional representation vote to ensure that minority groups are represented, the groups say the number needs to be increased.

The main parties say those issues can be fixed later.

"The constitution is not something that cannot be absolutely changed. It can always be amended later when needed," said Khadga Prasad Oli of the Communist Party of Nepal Unified Marxist Leninist.

Some among the country's majority Hindu population also believe the constitution should have restored Nepal as a Hindu nation. The Constituent Assembly voted down that proposal.

Police said thousands of officers were guarding streets across the nation and checking passengers on highways.

Opposition parties called a general strike to protest the constitution, but it had little effect on the traffic and markets remained open.

Neighboring India's external affairs ministry said in a statement that it was concerned with the situation in several parts of Nepal, calling for dialogue "that would enable broad-based ownership and acceptance."

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Gay right activists were among those who welcomed the new constitution, saying it respected gays' rights. "This constitution ensures our identity, rights, participation and inclusion; a better path ahead for Nepalese LGBTs," said Sunil Pant, a gay rights activist.

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