Manchester United manager Louis van Gaal said he was "sick" of questions about Wayne Rooney after his captain produced another below-par display in Sunday's 0-0 draw with Manchester City.

"I don't give any more answers about Wayne Rooney because I am sick of them," Van Gaal told his post-match press conference at Old Trafford.

Deployed at the tip of United's attack, Rooney, who turned 30 on Saturday, failed to muster a single shot on goal as City secured a point that took them back to the top of the Premier League table.

The England captain has scored only two goals in his last 16 league appearances, but Van Gaal refused to discuss his form.

"I have to talk every week about Rooney. Why?" he asked.

When it was put to him that it was because Rooney is one of United's star players, Van Gaal told his interlocutor: "Then you have to write it down. It is your opinion."

The result left United in fourth place in the table, two points behind City and second-place Arsenal and below third-place West Ham United on goal difference.