Image copyright Christopher Furlong Image caption Canada's largest school board will no longer book US trips for its students.

Canada's largest school board is cancelling new school trips to the United States until further notice.

The Toronto District School Board announced the decision citing "uncertainty" with regards to who may be affected by US President Donald's Trump's latest travel restrictions.

Twenty-five already scheduled trips will go ahead as planned.

The school board joins the Girl Guides of Canada and a few other schools in temporarily halting travel to the US.

Under the new US travel ban, citizens from Syria, Iran, Libya, Somalia, Sudan, and Yemen would not be permitted to enter the US, unless they have already been issued valid visas, for a 90-day period.

However, the ban is suspended pending a number of court challenges.

In a statement released on Thursday, Director of Education John Malloy said that the district school board faced "a difficult choice".

"We strongly believe that our students should not be placed into these situations of potentially being turned away at the border," said Mr Malloy.

"For the trips that will be continuing, should students with the appropriate documentation be denied entry to the US for no legitimate reason, the entire trip will return to Toronto and will not proceed."

The board is among the largest in North America with some 246,000 students in 584 schools throughout Toronto.

The school board says that, should the US travel restrictions be fully implemented, pre-approved trips will also be cancelled.

Oregon, Washington, Minnesota, New York, Massachusetts, and Hawaii have all launched legal challenges against the Trump administration's executive order.

Some individuals from those countries would be exempt from the order, including legal permanent residents of the US and dual nationals travelling on a passport from a country not on the list.

Last week, Canada's Girl Guides announced they would not be travelling to the US until further notice.

Greater Essex County school board in south-western Ontario decided last month to cancel a handful of trips over concerns about equity.

The Ottawa-Carleton District school board recently sent a letter to parents asking whether their children would participate in upcoming trips across the border to determine whether plans should go ahead.