Thailand's military has deployed around 6,000 police and soldiers across Bangkok to deter anti-coup protesters.

Army chief Prayut Chan-ocha has warned protesters that they - and even their families - face punishment under strict martial law.

But the military has so far taken a relatively light touch to marshalling the rallies, making several arrests but not using force.

Rumours that protesters would stage several rallies organised via social media across Bangkok brought 6,000 security forces to the streets on Sunday, blocking several roads to prevent any assembly.

"We have deployed 38 companies of combined forces of police and military at eight places across Bangkok. The situation so far is normal... there is no sign of any protest," deputy national police chief Somyot Poompanmoung told AFP.

Scores of police stood guard at the key Ratchaprasong intersection in Bangkok's commercial heart, while dozens of soldiers in riot gear were also seen nearby.

One of the apparent protest organisers, Sombat Boonngamanong - a fugitive Red Shirt activist - has defied a military summons to goad the army via his Twitter account.

"The people have no weapons, the people cannot use force, we can only annoy them (soldiers)," he tweeted on Saturday.

Protesters have gathered in small groups which peaked at around 1,000 last weekend, but have generally numbered in the low hundreds.

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Thai military condemns Australia's response

Thailand's ruling military says it is disappointed and gravely concerned by Australia's decision to stop joint military exercises and ban military leaders from travelling to Australia.

A Thai foreign affairs spokesman has told the ABC he hopes Australia will review the measure now that a roadmap back to democracy has been announced.

However, General Prayut says it will take more than a year for an election to be held.

In a joint statement issued on Saturday, Australian Foreign Minister Julie Bishop and Defence Minister David Johnston said three Australian military activities with Thailand had been postponed.

They include "a military operations law training course for Thai military officers; a reconnaissance visit for a counter improvised explosive device training exercise; and a reconnaissance visit for a counter terrorism training exercise", according to the statement.

The Government has also put in place a mechanism to prevent the leaders of the coup from travelling to Australia.

"The Australian Government continues to call on the military to set a pathway for a return to democracy and the rule of law as soon as possible, to refrain from arbitrary detentions, to release those detained for political reasons and to respect human rights and fundamental freedoms."

ABC/wires