Thailand's military chief has ruled out elections for at least a year to give time for political reforms and reconciliation of the factions.

In a national televised address more than a week after seizing power, army chief General Prayuth Chan-ocha defended the coup in the face of rising international alarm.

"The (ruling military regime) have a timeframe of one year and three months to move towards elections," he said.

General Prayuth outlined a three-phase process beginning with reconciliation between the factions which he said would take up to three months.

In the second phase, a temporary constitution would be drawn up and an interim prime minister and cabinet chosen to enact reforms.

"This process will take approximately a year, depending on the situation," he said.

"The third phase will be democratic elections.

"All that I have outlined will not succeed if all sides do not cease demonstrating politically.

"Thailand and the Thai people are facing many problems that require immediate attention and solutions.

"Enough time has been wasted on conflict."

In the address, General Prayuth justified the military takeover and the tough measures he introduced afterwards which have included censorship of the media and a ban on gatherings.

General Prayuth was seen sitting at a table with portraits of King Bhumibol Adulyadej and Queen Sirikit on a wall behind him.

"We cannot keep fighting each other just because we think differently," he said.

"Every side must find a way to cooperate."

Thailand's military seized power on May 22 and rounded up scores of political figures, academics and activists.

Authorities have abrogated the constitution, curtailed civil liberties under martial law and imposed a nightly curfew.

Around 300 people have now been held for periods of up to a week and those released have been threatened with prosecution if they continue political activism.

While the United States and other allies have urged a quick return to democracy, General Prayuth appealed for patience.

"All we are asking for is give us time to reform in order to mend our democratic system, to make it right, just and responsible," he said.

Thai economy slows after months of pressure

Thailand's stumbling economy is the priority for the military and General Prayuth has promised that the 2015 budget will be in order and public spending would be transparent.

Figures out on Friday showed private investment and consumption were stagnant in the run-up to the coup.

Gross domestic product shrank 2.1 per cent in the first quarter of 2014 as anti-government protests since November damaged confidence and scared off tourists.

The government of former prime minister Yingluck Shinawatra was in caretaker mode after dissolving parliament in December for a February election that was later annulled.

Ms Yingluck's government lacked the power to take policy decisions or to approve new spending.

The head of the central bank's macroeconomics department Mathee Supapongse says the overall financial picture is improving because the military government paying farmers money owed under a failed rice-subsidy scheme and it is also looking at infrastructure spending.

"But it's not easy to get to the central bank's economic growth forecast of 2.7 percent," he said.

"It's been half a year now and stimulus measures will not come all at once - but gradually; so the effect will rather be felt next year."

Mr Mathee was speaking after the release of central bank data that showed private investment in April was 4.7 percent lower than in the same month last year and consumption was down 0.8 percent.

It followed data earlier in the week that showed factory output fell for the 13th straight month in April, imports plunged and exports remained weak, underscoring the difficulty the military government faces in stopping a recession.

Activists say they plan weekend protests

Despite martial law and the ban on gatherings, small peaceful protests against the coup have been held continually in Bangkok.

For a second day on Friday, soldiers mounted a big operation at the central Victory Monument where crowds had gathered earlier in the week, sealing it off and preventing any groups from protesting.

Activists, spreading word through social media, say they will hold a big show of opposition at the weekend.

AFP/Reuters