Democratic Republic of Congo opposition leader Etienne Tshisekedi\'s party called for mass protests to \"protect\" the victory he claims to have won in disputed presidential polls. Jacquemin Shabani, secretary general of the Union for Democracy and Social Progress (UDSP), made the call for \"peaceful and democratic demonstrations\", without giving a time or place. The call comes amid growing crackdowns on opposition party protests, including one Wednesday in which demonstrators reported multiple injuries. The Independent National Electoral Commission (CENI) on Friday declared President Joseph Kabila the winner of the November 28 vote, provoking violent protests and looting in the capital and calls from opposition leaders for the international community to intervene. The European Union, the non-profit Carter Center and other election monitors have voiced serious concern about the credibility of the polls, citing problems in the vote count and the loss of huge numbers of ballots. The United States said that the elections were \"seriously flawed\", even if it is unclear whether the \"irregularities\" changed the outcome. \"We encourage the relevant Congolese authorities to closely review these cited irregularities and proceed with maximum openness and transparency,\" State Department spokeswoman Victoria Nuland said in a statement. \"We believe that the management and technical execution of these elections were seriously flawed, lacked transparency and did not measure up to the democratic gains we have seen in recent African elections,\" Nuland said. The US assessment, she said, is based on the observations of the teams fielded by the US embassy in Kinshasa as well as the views shared with US officials by other diplomatic missions and organizations such as the Carter Center. Kabila, in power since 2001, took 49 percent of the vote to 32 percent for Tshisekedi, his top rival, according to the CENI\'s tally. Tshisekedi immediately rejected the result and declared himself president. Police stopped opposition supporters from marching Tuesday in the eastern cities of Bukavu and Goma, whose mayors had banned protests. In Lubumbashi, the country\'s second-largest city, the elite presidential guard dispersed a protest Wednesday, injuring several people. About 30 local leaders from the the UDSP were marching toward the main courthouse to protest the closure of their headquarters. After local residents joined the march and numbers swelled to about 250, members of the presidential guard intervened, according to UDSP member Fabien Mutomb. \"It was a peaceful march,\" Mutomb said. \"We were surprised to see a military arsenal deployed in front of us. The presidential guard intervened violently.\" A report Tuesday by EU election observers was sharply critical of voting procedures in the recent poll, highlighting \"the lack of transparency and irregularities in the collection, compilation and publication of the results\". On Wednesday, representatives for both Kabila and Tshisekedi said the EU report should have gone further in describing who should actually have won the election.