A Mexican girl called the "Greta Thunberg of Madin" and a Bangladeshi teen who created an app against cybercrime are two of the finalists in a prestigious children's award, organisers announced Thursday.

The third finalist of this year's KidsRights International Children's Peace Prize -- seen as one of the most important global awards recognising the work of children -- is a young Irish activist who wrote the first school "survival guide" for girls with autism.

All three have received wide praise from Nobel Peace Prize laureate Archbishop Desmond Tutu, the patron of the Dutch-based award.

Ivanna Ortega Serret, 12, raised almost a million dollars and 67,000 signatures for a petition to help fight water pollution and clean up Madin dam, northwest of Mexico City, KidsRights said.

An important water source for communities in the Greater Mexico City area, the dam has been heavily infested with a type of plant which proliferates in polluted water, local newspapers said.

One paper dubbed Ortega the "Greta Thunberg of Madin" after the Swedish teen activist who was a joint winner of the prize last year.

In Bangladesh, 17-year-old Sadat Rahman and his friends created an online application to protect teens from cybercrime after a 15-year-old girl committed suicide because of online bullying.

The "Cyber Teens" mobile app is already being used by 1,800 youngsters and has led to the capture of at least eight cyber criminals so far, said KidsRights, a children's rights foundation.

Rahman has also spoken to some 45,000 teenagers in Bangladesh about online security.

Siena Castellon, 18, from Ireland, created a website to help pupils with autism and severe learning disabilities.

She is also the founder of the Neurodiversity Celebration Week campaign, which encourages schools to recognise the strengths and talents of children with special needs, instead of focusing on their weaknesses and difficulties.

In May 2019, over 340 schools and 314,000 students across Britain, the US and Australia took part in the campaign.

"I am in awe of these children, whose powerful message is amplified by their youthful energy and an unshakable belief that children can, no must, improve their own futures," Tutu said in a statement.

The winner will be announced on November 13 in an online ceremony from KidsRights' headquarters in the Netherlands.