Tokyo, Jan 17 (IANS): The Tokyo Stock Exchange opened on Tuesday with a drop and the Nikkei fell below 19,000 points due to investor caution ahead of a speech by UK Prime Minister Theresa May, who is expected to outline her government's Brexit strategy.

After one hour of trading, the Nikkei index suffered a drop of 182.81 points or 0.96 per cent and stood at 18,912.43 points.

At one point it fell 1.29 per cent to its lowest level in five weeks, Efe news reported.

Meanwhile the second indicator Topix, which tracks all domestic companies of the exchange's First Section, lost 15.06 points or 0.98 per cent, and stood at 1,515.58.

May is expected to deliver a speech on her negotiation plan with the European Union (EU) once Britain triggers Article 50 of the Lisbon Treaty, which establishes a two-year negotiation period on the departure of an EU country.

Her speech will reveal what London is looking for in its future relationship with the EU, although it is not expected to reveal too many details in order not to prejudice the negotiations.

Still, wary investors are waiting for clues about the process and its impact on the global economy.

The banking sector led the losses, followed by glass and ceramic products, and rubber.