(Adds details, background) BAGHDAD, Dec 5 (Reuters) - At least 14 people were killed and 28 wounded by a car bomb near a Shi'ite mosque in central Baghdad on Wednesday, the worst attack in the capital in more than two months, police said. The blast occurred at about 5 p.m. (1400 GMT) as worshippers were gathering for evening prayers. It also came minutes before visiting U.S. Defense Secretary Robert Gates began a media conference in the heavily fortified Green Zone across the Tigris River. Bursts of gunfire could be heard after the blast and Reuters witnesses reported seeing plumes of thick black smoke rising from the blast area in a busy street lined with shops. It was the worst attack in Baghdad since 32 people were killed in twin car bombings in the predominantly Shi'ite district of Bayaa in city's southwest on Sept. 26. On Nov. 23, 13 people were killed and 57 wounded by a bomb hidden in a box of birds at a popular outdoor pet market in central Baghdad. Violence across Iraq has fallen to the lowest levels in almost two years after a "surge" of 30,000 extra U.S. troops, but U.S. commanders warn the threat of attacks by Sunni Islamist al Qaeda or Shi'ite militias remains high. Gates made an unannounced visit to Iraq to urge its leaders to take advantage of declining violence and work towards reconciling Iraq's Shi'ite and Sunni Arab communities. One person was killed by a car bomb near a police station in Mosul hours before Gates touched down in the northern city. Car bombs in Baquba and Kirkuk, another two cities north of Baghdad, killed at least seven more. (Writing by Paul Tait, Editing by Dean Yates)
