Syrian President Bashar Assad rejected claims that Syria's alliance with Iran had been weakened by Damascus' participation in last month's US-sponsored Mideast peace conference, saying Thursday that the two countries' ties will never be shaken. Assad made the comments as he inaugurated two joint Syrian-Iranian industrial projects - factories for cars and cement. He was joined at the ceremonies by the Iranian industry and housing ministers. The November conference in Annapolis, Maryland, which relaunched Israeli-Palestinian peace negotiations, was widely seen as also aimed at isolating Iran by bringing together Arab nations. US officials have expressed hopes that Syria's attendance would mark a start to easing it out of its alliance with Teheran. Iranian President Mahmoud Ahmadinejad and other top officials denounced the conference, and some officials expressed surprise over Syria's participation - though none directly criticized it. Speaking at the auto factory, Assad said, "inaugurating this plant in partnership with our Iranian brothers and officials is a response to those who tried to circulate (reports) ... that relations between the two countries have been shaken." "I confirm, on this occasion, that relations will not be shaken for any reason or under any circumstance," Assad said at the factory in Hasya, some 160 kilometers north of the Syrian capital, Damascus. according to the official SANA news agency. Syria and Iran have growing economic ties, with the annual two-way trade estimated at about US$200 million. The size of Iranian investments in Syria has reached around US$2 billions in sectors such as power generation, automobiles, cement and agriculture. Syria is Iran's closest Arab ally. The two countries have had close relations since 1980 when Syria sided with Persian Iran against Iraq in the 1980-88 Iran-Iraq war. The $50 million International Syrian-Iranian Factory for Cars is the second car venture between the two countries in less than a year. It will have an initial production capacity of up to 15,000 cars a year and would likely increase to reach 35,000 cars annually at its final stage, SANA said. In March, Syria and Iran inaugurated the first joint car project in the industrial city of Adra near Damascus. Assad and the Iranian ministers also inaugurated a new cement plant in the northern city of Hama, some 210 kilometers northwest of the Syrian capital. The factory that had cost US$250 million has a production capacity of 1.1 million tons annually, SANA said. The project, which would create some 400 jobs, was initially agreed upon during a visit by then Iranian President Mohammed Khatami to Syria in mid 1999. The project is financed by the Kuwait Fund for Economic Development and the Iranian company has provided all the necessary equipment.