NEW DELHI (Reuters) - Indian Prime Minister Manmohan Singh faces more political headaches after the Supreme Court pressed for deeper probes into a multi-billion dollar corruption case and a ruling coalition ally was implicated in the scandal. Allegations the government may have lost up to $39 billion in revenues after firms were awarded telecoms deals at rock-bottom prices in return for kickbacks have rocked the ruling coalition and compounded the fragility of India's fragile investment climate. The Supreme Court, increasingly assertive under its new chief justice, told the federal police agency to go after more company executives and politicians and set up a special court to investigate India's biggest graft case in decades. One Indian company executive, a former telecoms minister and two other aides have been arrested in the scandal. "They are part of a wider conspiracy," a Supreme Court bench was quoted on Friday by local media as saying.