MADRID, November 29 (RIA Novosti) - Russia will push for reform of the Organization for Security and Cooperation in Europe at ministerial talks in Madrid starting on Thursday, amid U.S. allegations that it is trying to weaken the OSCE.

Russia stepped up its calls for changes to the OSCE after its main election monitoring arm, the Office for Democratic Institutions and Human Rights (ODIHR), refused to send its observers to Russia's parliamentary elections set for December 2, citing visa delays and "unprecedented restrictions."

Spain will be hosting the OSCE foreign ministerial council meeting as part of its presidency of the 56-nation human rights and security watchdog, which comprises European countries, the United States, Canada, and several ex-Soviet states.

Russia will be represented at the two-day meeting by Foreign Minister Sergei Lavrov, who announced on Wednesday that proposals to reform the OSCE would be raised. However, he said the issue would not be central to the meeting's agenda.

After the OSCE ODIRH announced that it would not be attending Russia's elections, President Vladimir Putin accused the United States of pressuring the organization.

"According to our data, this has once again been done on the U.S. State Department's recommendation, and we will take this into account in our intergovernmental relations with that country," the president said on Monday.

Washington angrily hit back at the allegations, and accused Russia of trying to undermine the OSCE's election monitoring work.

U.S. Under Secretary for Political Affairs Nicholas Burns said on Wednesday: "This allegation made by President Putin the other day is completely unfounded, it's untrue."

Burns challenged Putin to prove his claims: "It was interesting to note that in the statement that he made, President Putin said he had some information. Well, he should divulge that information."

The diplomat said Washington backs the ODIHR's decision not to attend Russia's State Duma elections, and that "The United States will oppose every move to weaken the ODIHR."

Although the OSCE is recognized by Western countries as the main authority on election monitoring, whose approval is a key requisite to declaring elections free and fair, Russia has in the past accused the organization of bias toward pro-Western opposition parties.

The OSCE played a key role in unveiling alleged ballot rigging in the 2004 Ukrainian presidential elections, leading to an election re-run in which a pro-Western candidate, Viktor Yushchenko, defeated his pro-Kremlin rival Viktor Yanukovych.

Moscow's proposals to reform the OSCE have been supported by former Soviet republics Uzbekistan, Belarus and Kazakhstan.

The OSCE ministerial council meeting is also set to address Russia's moratorium on the Conventional Forces in Europe Treaty, and the OSCE's mission in Kosovo amid increasing uncertainty over the breakaway province's future status.