Non-Governmental Organizations have been largely shut out of the United Nations climate summit in Copenhagen as security is ramped up in accordance with the arrival of heads of state from around the world.

The UN has denied access to thousands of registered NGO conference participants due to problems with both the accreditation process and capacity at the conference venue, the Bella Center.

The venue fits a maximum of 15,000 people but in excess of 40,000 have requested access. This has resulted in long queues and excessive crowding outside the Bella Center all week.

Today, the number of NGO observers allowed inside is restricted to 1000 while only 90 can enter on the final day of the conference.

A collective of 50 NGOs have written to COP15 president Lars L?kke Rasmussen and UNFCCC executive secretary Yvo de Boer to complain about the restrictions.

"It is unacceptable that civil society observers should be limited in this forum, and we hope that the UNFCCC Secretariat will recognize and reverse this undemocratic action," the letter reads.

"The negotiations under the UNFCCC/ Kyoto Protocol framework have a huge and increasing impact on the lives of ordinary people all over the world."

"Their participation in the climate negotiations as members of civil society is absolutely crucial for ensuring that the Copenhagen outcomes are both just and effective," it continues.

?Action Aid, Friends of the Earth, Third World Network, Christian Aid and CAN are among the 50 NGOs which have signed the letter.

The Danish Foreign Ministry has created an alternative venue for NGOs in response to the issue. Each venue will be equipped with television links to the Bella Center.