Poland's chief prosecutor said an initialexamination of black boxes from the aircraft that crashed over the weekend, killing the Polish president and dozens of the country's top officials, showed no evidence that passengers instructed the pilots to land.

The remarks by Poland's Prosecutor General Andrzej Seremet at a news conference Monday countered widespreadspeculation in Poland and Russia that Polish President Lech Kaczynski might have ordered the pilots to land in heavy fog.

Investigators appeared increasingly focused on pilot error as the likely cause of the crash. Polish and Russian officials both effectively ruled out technical error in the Russian-built Tupolev-154. Ninety-six people died in Saturday's accident, including the entire high command of the Polish military, Poland's central bank governor and national-security chief, and Mr. Kaczynski and his wife, Maria.

'Weather conditions were as bad as they could get. We don't know what the human factor was,' said Defense Minister Bogdan Klich, speaking on Poland TVN24 television. 'For the time being we can only say that the risk there's been any technical fault at the plane is close to zero.'

Language barriers may have contributed to the crash. One of the controllers at the airfield said in a verbatim interview published in Russian daily Komsomolskaya Pravda that the pilots and controllers had trouble communicating in a mix of broken English -- the global standard for air-traffic controllers -- and broken Russian.

The lack of an obvious cause of the crash has fueled speculation, including from former Polish President Lech Walesa, that the pilots may have come under pressure to land from President Kaczynski.

Mr. Seremet said specialists would examine background noise on recordings obtained from flight recorders to check for any traces of conversations that might change that initialconclusion. He confirmed that the control tower had discouraged the pilots from landing because of the density of the fog at Smolensk airport at the time.

According to Aviakor, the Russian company that overhauled the Polish plane in December, the Tupolev was equipped with an electronic system that should have warned the pilots the plane was dangerously low. The system may not have been the most current standard, which would have given the crew more time to react.

Bulgaria said Monday it was grounding its presidential Tupolev-154, pending the outcome of the Polish-Russian crash investigation.

Marc Champion and Marcin Sobczyk

• examination [ig,zæmi´neiʃən] n.检查；考试；检验 (初中词汇)
• conference [´kɔnfərəns] n.讨论(会)；会谈 (初中词汇)
• governor [´gʌvənə] n.总督；州长 (初中词汇)
• factor [´fæktə] n.因素；原动力；要素 (初中词汇)
• minister [´ministə] n.部长；大臣 v.伺候 (初中词汇)
• interview [´intəvju:] n.&vt.接见；会见；交谈 (初中词汇)
• obvious [´ɔbviəs] a.明显的；显而易见的 (初中词汇)
• pressure [´preʃə] n.压榨 vt.对...施压力 (初中词汇)
• background [´bækgraund] n.背景；经历；幕后 (初中词汇)
• flight [flait] n.逃走；飞行；班机 (初中词汇)
• conclusion [kən´klu:ʒən] n.结束；结论；推论 (初中词汇)
• system [´sistəm] n.系统，体系，制度 (初中词汇)
• presidential [,prezi´denʃəl] a.总统的；统辖的 (初中词汇)
• champion [´tʃæmpiən] n.冠军 vt.拥护 (初中词汇)
• initial [i´niʃəl] a.最初的 n.首字母 (高中词汇)
• speculation [,spekju´leiʃən] n.思索，推测；投机 (高中词汇)
• poland [´pəulənd] n.波兰 (高中词汇)
• technical [´teknikəl] a.技术的；专门性的 (高中词汇)
• weekend [´wi:kend, ,wi:k´end] n.周末休假 (四级词汇)
• polish [´pəuliʃ] a.波兰(人)的 n.波兰语 (四级词汇)
• widespread [´waidspred] a.广布的；普遍的 (四级词汇)
• increasingly [in´kri:siŋli] ad.日益，愈加 (四级词汇)
• outcome [´autkʌm] n.结果；后果；成果 (四级词汇)
• effectively [i´fektivli] ad.有效地 (六级词汇)
• speaking [´spi:kiŋ] n.说话 a.发言的 (六级词汇)
• landing [´lændiŋ] n.登陆；降落；楼梯平台 (六级词汇)
• density [´densiti] n.浓(稠)密；密度 (六级词汇)
• dangerously [´deindʒrəsli] ad.危险 (六级词汇)
• pending [´pendiŋ] a.迫近的；悬而未决的 (六级词汇)