Image copyright AP Image caption The rally was organised by electoral reform group Bersih

Thousands of yellow-shirted protesters have gathered in Malaysia's capital, Kuala Lumpur, to demand the resignation of Prime Minister Najib Razak.

The demonstrators want Mr Najib to face charges over allegations that billions were looted from his brainchild investment fund, 1MDB.

They were undeterred by a police ban and the arrest of a number of activists ahead of the planned action.

Mr Najib has denied any wrongdoing and says he will not be cowed by protests.

In a statement on his blog, Mr Najib called Bersih - the electoral reformist group which organised the protest - "deceitful". He said the group had become a tool for opposition parties to unseat a democratically elected government.

But his accusations were dismissed by Bersih deputy chair Shahrul Aman Shaari, who told the crowds gathered at the National Mosque: "We are not here to bring down the country. We love this country. We are not here to tear down the government, we're here to strengthen it."

This is the second rally organised by Bersih, which means "clean" in the Malay language, to demand Mr Najib's resignation in 15 months, and comes after weeks of rising tension between the "yellow shirts" and pro-government "red shirts".

Image copyright AP Image caption It is the second time in 15 months people have gathered to demand PM Najib Razak resign

Image copyright AFP Image caption Tension has risen between the "yellow shirts" and pro-government "red shirts"

The leaders of both sides, as well as a number of other Bersih activists, were arrested in the hours leading up to the rally - a move which was immediately condemned by human rights group Amnesty.

It demanded their immediate release, describing the activists as prisoners of conscience.

The arrests did not deter the protesters, however, some of whom chanted "save democracy" and "Bersih, Bersih".

"We want a clean government. We want fair elections," Derek Wong, 38, a real estate agent, told AFP.

A small group of red shirts gathered for an opposition protest.