The Chinese Premier, Wen Jiabao, is visiting South Korea amid continuing tension over the sinking of a South Korean warship in March, allegedly by North Korea. The issue is expected to dominate Mr Wen's talks with the South Korean President, Lee Myung-bak on Friday. International investigators have blamed North Korea for sinking the warship. But China has so far refused to join in the widespread condemnation of its old ally, Pyongyang. The Chinese state news agency Xinhua reports, the visit would strongly boost ties between the two countries.