File photo of Subramanian Swamy.

BJP lawmaker Subramanian Swamy today asked the Enforcement Directorate (ED) to speed up the inquiry against Robert Vadra over allegations that he has acquired a "benami" property in London."I think the case is already under investigation by the ED and it is only a matter of time before a case is registered for summoning of (Robert) Vadra", Mr Swamy, who is in Beijing while on his way to Kailash Manasarovar yatra in Tibet, said."There is no doubt Vadra has property in London through benaamis," he said referring to reports in the media today that the government has begun a new investigation against Mr Vadra to determine if a controversial arms dealer bought a "benami" or proxy-owned mansion in London for him in 2009.Mr Vadra's legal firm has denied that he owned the London property directly or indirectly. It also denied Mr Vadra has any business ties with an arms dealer or his aide.