Dewar has written to David Mundell urging the Scottish Secretary to work on cutting restrictions which currently limit the amount of flights between China and the UK.
Flights to China – one of the world’s largest economies – are only routed to London and only two operators offer the route.
Routes between the UK and non-EU countries are governed by bilateral agreements, which mean that flights between the two countries offered by UK and Chinese airlines have to be balanced with each other.
In his letter Dewar argues that there are many Chinese aircraft operators who are interested in flying to UK airports.
But the frequency of Chinese flights to the UK is limited by the number of UK operators currently offering the route.
“If we constrain Chinese operator connectivity to the UK to the level of growth currently offered by UK operators to China we will effectively deny the opportunity for overall growth between our markets,” Dewar said.
Dewar argued that the UK should keep promoting liberal access arrangements to other countries during the Brexit process to promote the message that the country is “open for business”.
He said: “To be clear, a balanced policy now has the potential to hamper Scotland’s and the UK’s connectivity with China. Edinburgh is the second most popular location for Chinese visitors and the pursuing of this approach would give me great concern.”
With talks on flight agreements expected to be held shortly, Dewar called on the UK to negotiate a “generous increase” in the number of routes” for all operators in both countries.
He added that there should be no restrictions on the airports involved.
“The alternative of restricting some or all new capacity to London would in effect negate the benefit where runway capacity will not be available for a number of years and directly constrain the growth potential of the Scottish economy,” Dewar said.
“As the economy with the largest growth potential and relatively immature aviation connectivity, the strategy and approach taken on the Chinese market can set the scene for many similar conversations over the coming years. Put simply, the UK should seek to maximise connectivity to this huge and growing economy to harvest the enormous opportunities for trade and tourism.”
Last night a UK government spokeswoman said: “Increasing trade links with key markets like China will boost exports, further open up tourism opportunities in the UK, and strengthen local economies.
“That’s why we are looking to cut restrictions on the number of flights between the UK and China. Talks are ongoing.”