WARSAW, October 10 (RIA Novosti) - Polish President Lech Kaczynski will sign on Saturday the European Union reform treaty, also known as the Lisbon Treaty, the president's office said.

The reform treaty, signed in December 2007 to streamline decision-making following the bloc's expansion, cannot come into effect until ratified by all 27 member states. Poland and the Czech Republic remain the only EU states to ratify the document after Ireland voted in its favor in a referendum on October 3.

The signing ceremony will be held at the presidential palace in Warsaw at 10.00 GMT and will be attended by senior EU officials, including President of the European Commission Jose Manuel Barroso and European Parliament President Jerzy Buzek.

The Polish president has previously said he would sign the Lisbon Treaty only after it is ratified by Ireland.

Ireland was the only nation constitutionally required to put the decision to a referendum. The Irish voters approved the document last Saturday in a second referendum after their first "no" vote to the treaty in June 2008.

The Czech Republic has been reluctant to approve Lisbon Treaty, citing concerns that the reforms would diminish Czech sovereignty. However, Czech Prime Minister Jan Fischer reassured EU officials on Wednesday that Czech President Vaclav Klaus would soon sign the document.

Russia has said the ratification of the EU reform treaty will contribute to developing Russia-EU relations.