Updated April 29, 2019 12:17:54Australian dollars have fallen to a low of 70.9 US cents on the Australian dollar against the US dollar after Federal Treasurer Scott Morrison’s morning morning tweet.

Key points:Mr Morrison has hit out at Mr Trump for the border wall proposalThe currency has been on a slide since the end of SeptemberA sharp drop in US interest rates has helped the Australian Dollar to fall to a fresh lowThe dollar has tumbled to its lowest level since September 8 when Mr Morrison said a “beautiful” border wall would be built in Australia, sparking a sharp fall in the value of the Australian currency.

Mr Morrison’s tweet came just hours after the US president announced a series of border security measures including the hiring of 5,000 new Border Patrol agents and a surge in border protection officers.

Mr Trump also said he would begin building a border wall in the US with Mexico.

The Australian dollar has been tumbling against the dollar since Mr Morrison made the statement on Wednesday morning, falling to 70.2 US cents at 11:47am (AEST).

It has been in a bear market for much of the past week, falling from a high of $US70.75 a dollar at the start of the month.

“I will build a great wall, and nobody builds walls better than me,and Mexico pays for that wall,and we will have great borders and borders will stay secure,” Mr Trump said.

But a sharp drop this morning in US yields has helped to drive the Australian pound lower, to US 1.2 per cent from 1.6 per cent on Wednesday.

It is now trading at US 1 per cent.

The US dollar is on a steep slide after falling sharply earlier this month, following a sharp sell-off in Chinese shares.

The strong US dollar has helped push up the Australian Treasury’s foreign currency assets, which are an important gauge of the country’s foreign exchange reserves.

The Treasury has held the overnight US interest rate at 1.5 per cent since the beginning of the year, but it has held that rate at a range of 2 per cent to 1.25 per cent for much longer.

A stronger dollar also has helped lift Australian exports, which have fallen this year.

Analysts expect the strong dollar to remain a major drag on the economy, and the Bank of Australia has warned of a “rebound” in the currency.

Topics:currency,currency-and-monetary-policy,foreign-affairs,federal-government,government-and-“government-to-government”,business-economics-and,national-security,australiaFirst posted April 28, 2019 10:59:35More stories from Australia