DUSHANBE (Reuters) - Tajikistans lower house of parliament ratified an agreement on Wednesday to demarcate its border with China, ending a century-old conflict over disputed territory high in the Pamir mountains of Central Asia. Tajik Foreign Minister Khamrokhon Zarifi said the decision to cede 4 percent of the disputed land to China represented a great victory for Tajik diplomacy. Opposition politicians said the agreement flouted the constitution of the impoverished former Soviet republic. The dispute over 28,500 sq km of land, an area approximately the same size as Albania, dates back to the end of the 19th century. Neither the Tsarist Russian empire nor the Soviet Union was able to reach agreement with China over their common border. Zarifi said the agreement with China would result in Beijing controlling 1,100 sq km of the disputed region, equivalent to less than 1 percent of Tajikistans total land area. The agreement must first be ratified by Tajikistans senate, a formality in a country tightly controlled by veteran President Imomali Rakhmon. China has invested hundreds of millions of dollars in Tajikistan, the poorest of five former Soviet republics in Central Asia, and given favourable loans for infrastructure and other projects. Parliamentary deputies said they had been unaware of the intergovernmental agreement with China until several days ago. The ratification of this protocol contradicts the constitution, which says the territory of our state is united and indivisible, said Mukhiddin Kabiri, chairman of the Islamic Revival Party of Tajikistan and one of only two opposition members of parliament.