Register now for FREE unlimited access to Reuters.comBANGKOK, Jan 6 (Reuters) - China has notified downstream neighbours it is holding back the Mekong River flow at a hydropower dam on the waterway's upper reaches for 20 days, as part of a new data-sharing pact, the Mekong River Commission (MRC) and Thailand said on Wednesday. The statements came a day after a new U.S.-backed monitoring system said China had failed to notify downstream countries of water restrictions that started on Dec. 31.China agreed last October to share water data with the MRC, an advisory body to Thailand, Laos,...…Register now for FREE unlimited access to Reuters.comBANGKOK, Jan 6 (Reuters) - China has notified downstream neighbours it is holding back the Mekong River flow at a hydropower dam on the waterway's upper reaches for 20 days, as part of a new data-sharing pact, the Mekong River Commission (MRC) and Thailand said on Wednesday. The statements came a day after a new U.S.-backed monitoring system said China had failed to notify downstream countries of water restrictions that started on Dec. 31.China agreed last October to share water data with the MRC, an advisory body to Thailand, Laos,...WW…