UPDATE 4-Oil price probe widens, US senator wants Justice Dept help
* Source says Dutch trader Argos Energies being investigated
* Sen. Wyden calls for Justice Dept to look at US price impact
* Finnish refiner Neste Oil says asked for information
* Oil market liquidity not affected -Platts
By Simon Falush and Timothy Gardner
LONDON/WASHINGTON, May 17 (Reuters) - A European probe into possible oil price manipulation expanded with the investigation of a small niche trading house in the Netherlands, while a key U.S. senator on Friday called for the Justice Department to join the investigation.
Dutch trading house Argos Energies, a mid-sized trading company that deals in physical oil products and owns storage facilities, was visited by inspectors from the European Commission on Tuesday, a source familiar with the investigation said on Friday.
The visit occurred on the same day that authorities raided the London bureau of pricing agency Platts, and the offices of Statoil, Royal Dutch Shell and BP in the biggest cross-border action since the probe into rigging of Libor benchmark interest rates.
In Washington, the chairman of the Senate's energy committee asked the Justice Department to investigate whether alleged price manipulation has boosted fuel prices for U.S. consumers. Continued...