The US dollar slipped on Monday as optimism that the US and China will reach a trade deal reduced demand for safe haven currencies, and as investors waited on the Federal Reserve's meeting this week. US President Donald Trump said on Monday he expected to sign a significant part of the trade deal with China ahead of schedule but did not elaborate on the timing.

The comments come after the US Trade Representative's office and China's Commerce Ministry said on Friday that US and Chinese officials are "close to finalizing" some parts of a trade agreement, with talks to continue. The trade war between the US and China has been blamed for adding to global economic weakness, which in turn has prompted central banks globally to cut rates.

"Positive trade headlines continue to support our view that trade tensions are easing," said Win Thin, global head of FX strategy at Brown Brothers Harriman. The dollar index against a basket of six major currencies fell 0.07% to 97.765. The greenback gained 0.19% against the Swiss franc to 0.9962. The Australian dollar, which is highly sensitive to the Chinese economy, rose 0.07% to $0.6827 US dollars. Hopes that Britain will reach a deal to leave the European Union, and avoid a disorderly exit, also boosted risk sentiment on Monday.