Troops and protesters play cat-and-mouse in Bangkok

One group of peaceful protesters evaded soldiers, police and roadblocks to stage a demonstration in the city's commercial centre in what has become a now daily dance with authorities.

Police said they had arrested "some" of the protesters who had gathered at a walkway linked to a major shopping centre.

Political assemblies of more than five people were banned under martial law declared by Army Chief Prayut Chan-O-Cha two days before he seized power in a coup on May 22.

But small, daily protests have been held in the capital since Prayut ousted the civilian government.

A flashmob of around two dozen people gathered at midday near the downtown shopping mall, according to an AFP reporter.

Security forces, many carrying riot shields, swiftly encircled the rally and were briefly backed by an armoured humvee with a soldier manning a mounted machine gun.

Protesters unfurled a giant poster of Prayut's face with the words "Thailand 1984" emblazoned below, a reference to George Orwell's anti-authoritarian novel which has become an accessory for many of the Bangkok protesters.

"I want to call for my freedom... there should be equality for everyone," protester Nantachaporn told AFP, giving only one name.

Protesters also gave a three-fingered salute, in an apparent nod to the fictional people's power movement from "The Hunger Games" film.

"So far there is only one protest in the city... we have arrested some of the protesters," deputy national police chief Somyot Poompanmoung told AFP, without specifying how many had been held.

Earlier, Somyot said more than 6,000 soldiers and police had been deployed at eight locations across the city.

In a game of cat-and-mouse played out over social media, the protesters appeared to wrongfoot authorities, instead gathering at the shopping centre.

Other small protests were reported, with at least one person detained by police earlier in the commercial district.

Necessary evil or pretext for coup?

General Prayut has warned protesters that they -- and even their families -- face punishment under strict martial law, which has imposed sweeping curbs on freedoms.

So far his troops have taken a relatively light touch to marshalling the rallies, making several arrests but not using force.

But rights groups have condemned Prayut for using intimidation to deter protesters, summoning likely dissenters to army camps as well as moving to stifle the media.

The number of demonstrators peaked at around 1,000 last weekend, but they have generally met in small groups.

Among them are members of the Red Shirt movement -- supporters of the ousted government of Yingluck Shinawatra and her billionaire brother Thaksin, who lives in self-exile to avoid prison for a corruption conviction.

But there are also ordinary pro-democracy campaigners drawn from the Bangkok middle class.

General Prayut said he was prodded into taking power to restore peace and order after several months of anti-government protests which saw 28 people killed and hundreds of others wounded.

The tough-talking army chief has said democracy will not be restored for at least a year as the nation first needs vaguely-defined reforms, while warning that protests could alter this timeframe.

Critics accuse him of using the violence as a pretext for a long-planned power grab by the military and its supporters within the Bangkok-based elite.

They loathe the former premier Thaksin and accuse him of toxifying Thai politics since his emergence in 2001.

Thaksin, who draws widespread support among the rural poor of the north and northeast as well as sections of the urban middle and working classes, was ousted in another military coup in 2006.

Parties led or aligned to him have won every election since 2001.