The Great Britain Davis Cup squad - including Andy Murray - has delayed its planned departure to Belgium for the final against the hosts next week.
Security fears in Brussels have been of "great concern" to the International Tennis Federation (ITF) ahead of the final after Belgium put the capital on maximum security alert on Saturday.
It follows last Friday's deadly attacks in Paris, of whom one suspect from Brussels is at large.
Security of players, fans, media and working staff remains our highest priority
"Over the last week, the ITF has been in constant contact with the relevant authorities, the Royal Belgian Tennis Federation, the Lawn Tennis Association and our risk assessment company and this dialogue continues today," the ITF President David Haggerty said in a statement.
"We're aware that Belgium has raised the terror alert level for Brussels.
"This greatly concerns us but, at the present time, we are still continuing with preparations for the final.
"What I said last weekend is true today: security of players, fans, media and working staff remains our highest priority."
The three-day final is due to start on Friday at the 13,000-seat Flanders Expo in Ghent, 35 miles north west of Brussels.
Anderlecht's match at Lokeren in Belgium's top football league was postponed on Saturday, with the league saying "safety could not be guaranteed".
The national team's football friendly against Spain was called off last week due to increased terrorist threat.