A court in Bucharest ruled that Mircea Basescu, the president’s younger brother, should be remanded in custody for 30 days for allegedly taking a 250,000 euro bribe from a relative of convicted underworld boss Sandu Anghel.

Prosecutors allege that he received the money through a middleman in exchange for a promise to intervene to secure Anghel’s release.

Anghel, also known as Bercea Mondial, “Bercea the Global”, was recently sentenced to eight years and nine months without parole for stabbing his nephew to death in 2011. Mircea Basescu is godfather to Anghel’s granddaughter.

On Thursday, President Basescu strongly denied any involvement in the case. Media reports and some politicians have implied that he allegedly knew about the arrangement.

Prime Minister Victor Ponta has asked the president to step down from his position “to eliminate any pressure on the judiciary”.

Ponta’s centre-left government and President Basescu have a long history of disputes, which culminated in a referendum on the impeachment of Basescu in July 2012.

An impulsive and divisive figure, Basescu has failed to defuse tensions with the government and parliament, accusing most politicians of being corrupt and of not supporting a faster pace of reforms.

Romania is still considered one of the most corrupt states in the European Union and has made only limited progress in fighting corruption and organised crime since it joined the EU in 2007.

Bucharest has drawn repeated criticism from the European Commission for its failure to tackle the problem.

But in recent years, the number of high-ranking officials sentenced for graft has increased significantly.

More than 1,000 people were convicted of corruption in 2013 alone. Those sent for trial included six ministers and parliamentarians, five county council heads, 34 mayors and deputy mayors, judges, lawyers and managers of state-run companies. Most of the cases involved bribery, trading in influence, tax evasion, and fraud related to EU funds.

By comparison, no member of government or lawmaker was convicted of corruption between 2002 and 2009.