TASHKENT, May 25 (AFP) - The United States Tuesday urged Uzbekistan to deepen its market reforms if the former Soviet republic wants to boost direct foreign investment. "The quicker and deeper the economic reforms will be, the quicker will be development in this area (of direct foreign investment)," US ambassador-at-large Steven Sestanovich said. He was speaking after a meeting here of a US-Uzbek joint commission. Trade volume between the United States and Uzbekistan declined 34 percent to 181 million dollars in 1998, he said. Uzbek laws preventing foreign firms from repatriating their earnings and the unconvertible Uzbek currency, the som, deter investors from doing business in the resource-rich republic, the ambassador said. To further market reforms, including promises by Uzbekistan to make the som convertible by next year, Washington this year will issue Uzbekistan a 33 million dollars grant, Sestanovich said. The two sides also signed several bilateral agreements, including a pledge to cooperate on military reforms to help Uzbekistan better guard its borders and fight terrorism on its territory, Sestanovich said. The United States further asked Uzbekistan to help broker a political settlement to the Afghan civil war by hosting a six-plus-two grouping of the nations bordering the war-torn country -- China, Iran, Pakistan, Uzbekistan, Tajikistan and Turkmenistan -- with the United States and Russia. Central Asian attempts to mediate in the war have so far been unsuccessful. Negotiations in March between the Afghan opposition and the Taliban militia in Turkmenistan failed to bring about a lasting political settlement.  