* Polish government has enacted judicial reforms

* Reforms put government on collision course with Brussels

* Government has dismissed EU criticisms

By Anna Wlodarczak-Semczuk

WARSAW, Dec 5 (Reuters) - Poland's Supreme Court ruled on Thursday that a judicial oversight panel introduced by the nationalist government to appoint judges was not sufficiently independent.

The decision could encourage legal challenges to rulings made by judges nominated by the panel, the National Council of the Judiciary (KRS), potentially causing delays or even chaos in the judicial system, legal experts said.

It was the latest complication for judicial reforms introduced by the right-wing Law and Justice (PiS) party government that have been condemned by Poland's European Union partners as politicising the courts.

The EU's top court said last month it was up to Poland's Supreme Court to decide on the independence of the KRS and another body set up under the reforms for disciplining judges.

The Supreme Court stated that the current KRS "is not an impartial body independent of the legislative and executive authorities".

Most of the people serving on the KRS were chosen by the PiS-dominated parliament.

Rulings of the Supreme Court are binding only in a specific case, but legal experts said the decision meant cases ruled by judges appointed by the KRS may be questioned by parties on the basis that the judges had been unlawfully installed.

"This fact may be used as a tool to question various perfectly correct and just rulings, citing procedural matters. This is not a good situation", said Michal Laskowski, the spokesman for the Supreme Court.

The PiS has rejected Brussels' criticisms of its court reforms, saying its goal is to make the system more efficient and fair.

The Supreme Court is led by a judge, Malgorzata Gersdorf, who was appointed before the PiS came to power. The government has backed off attempts to force her into early retirement under pressure from the EU.

Poland's other top court, the Constitutional Tribunal, rules on the validity of laws. It is headed by a judge whom PiS leader Jaroslaw Kaczynski refers to as "a close friend". (Reporting by Marcin Goclowski, Anna Wlodarczak-Semczuk, and Joanna Plucinska, Editing by Timothy Heritage)