BUCHAREST (Reuters) - Thousands of Romanians rallied in Bucharest and cities across the country on Sunday to protest against government plans to decriminalize some offences and pardon some convicted prisoners through emergency decrees that critics say threaten to undermine a crackdown on high-level graft.

The new cabinet of Prime Minister Sorin Grindeanu last week unveiled the draft decrees that have been criticized by the president, the prosecutor general, the supreme court, the chief anti-corruption prosecutor and the chief of the directorate fighting organized crime, as well as civil rights groups and diplomats.

All have expressed concern about the drafts, as well as a lack of transparency and the intention to legislate through decrees instead of going through parliament, despite having a strong majority there.

According to drafts, the government intends among other changes to decriminalize abuse of power actions causing financial damage of less than 200,000 lei ($47,500), an offence the leader of the ruling Social Democrat party is accused of inciting a third party to commit.

According to the drafts, the government also intends to pardon convicts sentenced to less than five years for committing certain crimes, and cut sentences by half for all prisoners aged over 60, those having a terminal illness or children to support, regardless of their crime.

The president, Klaus Iohannis, urged the government on Friday to scrap the decrees, which he said would undermine the rule of law and anti-corruption.

The government has not commented.

On Sunday more than 15,000 people in Bucharest gathered in freezing weather at University Square, the site of all major protests since Romania overthrew the communism in 1989.

"I was here during the revolution 27 years ago and I am noticing that almost nothing has changed since then, thievery ... still exists," pensioner Ioan Ilincuta said.

"I am protesting in the hopes that my children and grandchildren can see better times."

Protesters of all ages carried banners that read "We are awake", "We want justice, not corruption", chanted "Thieves" and marched towards government headquarters. Iohannis joined them briefly.

Thousands also rallied in the cities of Cluj, Timisoara, Iasi, Sibiu and several other cities across the country.

Smaller gatherings also took place outside embassies in London, Paris and Copenhagen, according to photographs posted on Facebook by Romanians living abroad.

Despite Romania joining the European Union in 2007 its legal system continues to be the subject of special monitoring by the European Commission, which has praised magistrates' efforts to fight widespread graft but noted that Romanian politicians have a history of trying to pass legislation which could weaken investigative powers.

(Reporting by Luiza Ilie; Editing by Greg Mahlich)