International sanctions against Iran are the "toughest ever", US Secretary of State Hillary Clinton said Thursday, adding that the US continues to believe there is time for diplomacy over Tehran's nuclear program.Speaking at a joint press conference with Libyan Prime Minister Abdurrahim El-Keib, Clinton also stated that the international community is united in preventing Iran from obtaining nuclear capabilities. "We are united in our concerns and condemnation of Iran’s actions that violate their international obligations, and we are united in continuing to press the Iranian regime to come to the diplomatic forum that the P-5+1 offers," she said.Clinton added that this unity has lead to "the toughest sanctions that the international community has ever imposed." The US secretary of state said that, coupled with the robust sanctions imposed on Tehran, the international community remains committed to reaching a settlement through diplomacy. "We want to begin discussions with Iran," she said. "They insist that their nuclear program is purely peaceful and if that’s the case, then openness and transparency, not only with the P-5+1 but also with the IAEA and the Security Council and the international community, is essential."Citing a statement on the Iranian nuke program released by China Thursday on behalf of the P-5+1, Clinton said that there is widespread agreement on the need for observers to be granted access to the Iranian military site at Parchin. Reports that Iran had formally contacted the International Atomic Energy Agency regarding a possible visit to the site were denied Thursday by Yukiya Amano, head of the UN nuclear watchdog.Clinton added her hope that Iran will come to the table prepared for "serious and sincere discussions" over its nuclear program.