TEHRAN (AFP) - Tehran said Tuesday a decision by the US Senate to tighten economic sanctions against Iran contradicted assertions by the US administration that it favoured talks on Iran’s disputed nuclear work. The measure shows “you cannot trust the gestures and claims of the US administration as (different) power centres exist” within the US political system, foreign ministry spokesman Ramin Mehmanparast said in a statement. The US Senate unanimously approved new economic sanctions Friday aimed at further crippling Iran’s energy, shipping and port sectors, a year after the US Congress passed tough restrictions against Tehran.