Macedonian Prime Minister Nikola Gruevski (C), greet supporters during a rally in the centre of Skopje on May 18, 2015.

Macedonian opposition demonstrators set up a protest camp outside the offices of embattled Prime Minister Nikola Gruevski on Monday as some 30,000 of his supporters took to the streets of the capital for a counter-rally.The pro-Gruevski demo took place outside the parliament building, just some two kilometres (1.5 miles) away from where around a thousand opposition supporters were camping out in front of government offices, according to AFP journalists.The centre-left opposition is seeking the conservative premier's resignation, accusing him of corruption, mass wiretapping and of fomenting ethnic tensions to hang onto power.Monday's rally, held under the motto "Strong Macedonia," was organised in response to Sunday's march through Skopje by about 20,000 opposition supporters seeking the resignation of Gruevski, in power since mid-2006.Gruevski's supporters, estimated by an AFP count to number more than 30,000, were still flocking to the parliament building late Monday, waving Macedonia's red and yellow flag and chanting "Macedonia! Macedonia!" and "Nikola! Nikola!"Meanwhile, the premier's detractors were digging in their heels after opposition leader Zoran Zaev urged them to stay on the streets in front of Gruevski's neo-classical government headquarters "until he goes".Heeding his call, hundreds of anti-Gruevski demonstrators set up camp on a lawn in the middle of a boulevard facing the prime minister's offices.The site took on a festival atmosphere with dozens of brightly coloured tents grouped around a small stage, some decorated with signs reading "Resignation!" and "Goodbye Nikola" as music blared from nearby loudspeakers.Police closed off part of the boulevard, causing a traffic jam that prompted local media to urge citizens to avoid the city centre.The rival demos have highlighted the deep divisions that plague the tiny Balkan country, which has been dogged by a political crisis since disputed elections last year and has been left reeling after a bloody clash between police and ethnic Albanian gunmen left 18 dead earlier this month.The deadly shootout in the northern town of Kumanovo was the worst violence since the country narrowly avoided civil war after an Albanian uprising in 2001.Separately, two key ministers and the intelligence chief stepped down last week after being linked to a long-running snooping scandal, in which Zaev's opposition Social Democratic Union of Macedonia (SDSM) accuse the ruling party of wiretapping up to 20,000 people, including politicians, journalists and religious leaders.Zaev has released snippets of the alleged recordings that appear to show widespread government corruption, a murder cover-up and other wrongdoings.Sunday's march called by the opposition SDSM brought many ethnic Albanians and Turks onto the streets as well as protesters from the majority Macedonian community.Ethnic Albanians make up about one quarter of Macedonia's 2.1 million population.Under pressure from the European Union, which Macedonia has applied to join, leaders of the country's four main parties met on Monday to try to defuse the crisis, but talks hardly got off the ground."We have not opened talks on any issue, because we first need to solve certain things," Zaev told reporters after the meeting.He said the issues included the equal status of all the participants "and guarantees on implementation of everything that would be agreed".He repeated that his party insisted that an interim government be formed without Gruevski in it.At the colourful opposition demonstration in front of the prime minister's office, protesters, whose number grew to some 1,000 on Monday evening, vowed to hold firm."I will stay here until Gruevski steps down," protester Sime Kardanovski, 38, told AFP.But those at the rival rally labelled such a scenario highly unlikely."Zaev is waisting his time. Even if early elections will be held he would lose," Vlatko Aleksov, a man in his 30s from Skopje, told AFP.

In Brussels, NATO Secretary General Jens Stoltenberg said the Alliance was closely following developments in Macedonia and stressed the necessity of avoiding violence and any escalation of the crisis.Half of the highly-polarised Macedonian-language media described Sunday's protest, which passed off peacefully, as a "grandiose" gathering, while pro-government outlets condemned it as a rally of those "who want to destabilise" Macedonia.